mpc85xx-p1010: re-enable TP-Link WDR4900

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>
(cherry picked from commit 301443da)

docs/user/supported_devices.rst

@@ -270,6 +270,10 @@ mpc85xx-p1010
 
   - RED 15w Rev.1
 
+* TP-Link
+
+  - WDR4900
+
 mpc85xx-p1020
 ---------------
 

targets/mpc85xx-p1010

@@ -5,3 +5,7 @@ device('sophos-red-15w-rev.1', 'sophos_red-15w-rev1', {
 })
 
 
+-- TP-Link
+
+device('tp-link-tl-wdr4900-v1', 'tplink_tl-wdr4900-v1')
+