Upstream added a standalone SPI kernel-loader which fixes the unbootable
image for the WDR4900. Thus, we can re-introduce this device to Gluon.

Signed-off-by: David Bauer <mail@david-bauer.net>

Specification:

SoC: MediaTek MT7628AN
RAM: 64MiB
Flash: 8MiB
Wifi:
  - 2.4GHz: MT7628AN
  - 5GHz: MT7612EN
LAN: 1x 10/100 Mbps

Flash instructions:
Flash factory image through stock firmware WEB UI.
Back to stock is possible by using TFTP and stripping down the Firmware
provided by TP-Link to a initramfs.

The flash space between 0x650000 and 0x7f0000
is blank in the stock firmware so I left it out as well.

Co-authored-by: Christoph Krapp <christoph.krapp@power.cloud>

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Note: Buffalo has introduced hardware changes without bumping the
revision number. 19.07 did not support the rb-variant so there's no need
to implement a migration for the rb-variant.
Every g300nh supported by Gluon should either be the s-variant or
been flashed wrongly.

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Note that it was wrongly marked as device class tiny in
commit 7fd7116e ("targets: add device-class flags") in the past,
the device has 64MB RAM and not 32MB.

Also, the device has no "led-running" assigned in DTS. The device has
three LEDs: "green:vpn", "green:lan" and "green:wlan". The first LED,
"green:vpn", has a "V" icon and was used to show the VPN connection
status in the vendor firmware. This LED will be used via the newly
added "led-boot" fallback in gluon-setup-mode. But will be unused
during normal operation due to the unassigned "led-running" in DTS.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

Gone due to
commit 45c84a11 ("ar71xx: drop target")

The CN/RU variant of the device has the same hardware
as the EU already supported, but contains a 16M flash chip.

Gone due to
commit 45c84a11 ("ar71xx: drop target")

ar71xx only supported the 8M variant

Specifications:
* SoC: AR7242 (Virian 400MHz)
* RAM: 64 MB DDR (W9751G6JB-25)
* Flash: 16MB SPI flash (S25FL129PIF)
* WiFi: AR9382 (2.4/5GHz) + 2x SE2595L
* LAN: 1x1000M (PEF7071V)

To install via EVA bootloader, a FTP connection need to be
established to 192.168.178.1 within the first seconds after power on:

  ftp> quote USER adam2
  ftp> quote PASS adam2
  ftp> binary
  ftp> debug
  ftp> passive
  ftp> quote MEDIA FLSH
  ftp> put lede-ar71xx-generic-fritz300e-squashfs-sysupgrade.bin mtd1

Co-Authored-By: J. Burfeind <github@aiyionpri.me>

Co-authored-by: Tim-Niklas Koch <info@tnkoch.de>
Co-authored-by: J. Burfeind <github@aiyionpri.me>

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Both are effectively the same hardware, the latter being Buffalos
replacement model.

Gone due to
commit 45c84a11 ("ar71xx: drop target")

Co-authored-by: Maximilian Baumgartner <aufhaxer@googlemail.com>

Gone due to
commit 45c84a11 ("ar71xx: drop target")

The DTS model name has been changed to "TP-Link Archer C6 v2 (EU/RU/JP)"
to distinguish it from the US version.

Closes #2533

Gone due to
commit 071cf7b2 ("Switch to Lua for target definitions")

Has prior been introduced as untested -> broken in
commit d586720c ("ar71xx-generic: add support for Ubiquiti NanoBeam M5")

Was commented out in the former commit.

Signed-off-by: Sebastian Schaper <openwrt@sebastianschaper.net>

Removed in 45c84a11 ("ar71xx: drop target").

Re-add mikrotik target

Note that previous images were generic ones and as such no migration
path is provided other than manually flashing the image via config-mode.

- [x] Must be flashable from vendor firmware
  - [x] Web interface
  - [ ] TFTP (untested, but possible according to OpenWrt wiki)
  - [ ] Other: <specify>
- [x] Must support upgrade mechanism
  - [x] Must have working sysupgrade
    - [x] Must keep/forget configuration (`sysupgrade [-n]`, `firstboot`)
  - [x] Gluon profile name matches autoupdater image name
        (`lua -e 'print(require("platform_info").get_image_name())'`)
- [x] Reset/WPS/... button must return device into config mode
- [x] Primary MAC address should match address on device label (or packaging)
      (https://gluon.readthedocs.io/en/latest/dev/hardware.html#notes)
  - When re-adding a device that was supported by an earlier version of Gluon, a
    factory reset must be performed before checking the primary MAC address, as
    the setting from the old version is not reset otherwise.
- Wired network
  - [x] should support all network ports on the device
  - [x] must have correct port assignment (WAN/LAN)
    - On devices supplied via PoE, there is usually no explicit WAN/LAN labeling on the hardware.
      The PoE input should be the WAN port in this case.
- Wireless network (if applicable)
  - [x] Association with AP must be possible on all radios
  - [x] Association with 802.11s mesh must work on all radios
  - [x] AP+mesh mode must work in parallel on all radios
- LED mapping
  - Power/system LED
    - [x] Lit while the device is on
    - [x] Should display config mode blink sequence
          (https://gluon.readthedocs.io/en/latest/features/configmode.html)
  - Radio LEDs
    - [x] Should map to their respective radio
    - [x] Should show activity
  - Switch port LEDs
    - [x] Should map to their respective port (or switch, if only one led present)
    - [x] Should show link state and activity