This backports the TP-Link Archer C50 v4.

We are dropping the following upstream commits. They add support for the
TP-Link recovery-flag which enabled the web-recovery. As they are not
needed for the router to work, we drop them for now.

28cd2ca base-files: sysupgrade: support additional mtd options
1e06482 mtd: add logic for TP-Link ramips recovery magic

This commit removes the broken flag from all devices in the mt76x8
subtarget.

The stability of the mt76 driver for the mt7628 and mt7612 has greatly
improved in the last half-year. It might be still behind ath9k and
ath10k but it is suitable for daily use.

This affects the following devices:

 - GL.iNet MT300N v2
 - TP-Link Archer C50 v3
 - TP-Link TL-WR841 v13

Signed-off-by: Martin Weinelt <martin@darmstadt.freifunk.net>

Adds a footnote with a link to an instruction on how to flash Gluon onto
AVM routers.

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

The driver has stablized enough to officially support ramips-mt76x8 devices
again. At least remove BROKEN for VoCore 2 (as it was supported before).

The ramips-mt76x8 target is marked as BROKEN.

Signed-off-by: Christoph Krapp <achterin@googlemail.com>

Signed-off-by: Christoph Krapp <achterin@googlemail.com>

Signed-off-by: Martin Weinelt <martin@darmstadt.freifunk.net>

Addition of the OCEDO Koala to the supported devices in the docs was
forgotten in 52bc028e.

This device is a dual 5GHz device. It is recommended to manually change the
radio of the first device to the lower 5GHz channels and the second radio
to the upper 5GHz channels.

This commit adds support for the new ipq40xx target.

Explain the magic of gluon.mk. The feature flag documention is moved into
this new page.

Adds support for Alfa AP121F USB powered travel router (looks like an USB ethernet adapter).
There is no factory image, but only a sysupgrade file for this router which can be installed using the inbuilt UBoot web interface.
Configure your PC with IP address 192.168.1.2 and connect the router using its RJ45 port. Hold the reset button while powering the device until all LEDs have flashed 3 times simultaneously. You can now access the fallback web interface using a web browser at http://192.168.1.1 and flash the sysupgrade file.