ramips: add support for TP-Link TL-WR841n v14

TP-Link TL-WR841n v14 is a router based on MediaTek MT7628N.

- MediaTek MT7628NN
- 32 MB of RAM
- 4 MB of FLASH
- 2T2R 2.4 GHz
- 5x 10/100 Mbps Ethernet

Installation:
- copy the
  'openwrt-ramips-mt76x8-tl-wr841n-v14-squashfs-tftp-recovery.bin'
  file to your tftp server root and rename it to 'tp_recovery.bin'.
- configure your PC running the TFTP server with the static IP address
  192.168.0.66/24
- push the reset button and plug in the power connector. Wait until
  the orange led starts blinking (~6sec)

Signed-off-by: Alexander Müller <donothingloop@gmail.com>
Signed-off-by: Alexander Couzens <lynxis@fe80.eu> [small modifications gpio-hog]

target/linux/ramips/image/mt76x8.mk

@@ -259,6 +259,20 @@ define Device/tl-wr841n-v13
 endef
 TARGET_DEVICES += tl-wr841n-v13
 
+define Device/tplink_tl-wr841n-v14
+  $(Device/tplink)
+  DTS := TL-WR841NV14
+  IMAGE_SIZE := 3968k
+  DEVICE_TITLE := TP-Link TL-WR841N v14
+  TPLINK_FLASHLAYOUT := 4Mmtk
+  TPLINK_HWID := 0x08410014
+  TPLINK_HWREV := 0x1
+  TPLINK_HWREVADD := 0x14
+  TPLINK_HVERSION := 3
+  IMAGE/tftp-recovery.bin := pad-extra 64k | $$(IMAGE/factory.bin)
+endef
+TARGET_DEVICES += tplink_tl-wr841n-v14
+
 define Device/tplink_c20-v4
   $(Device/tplink)
   DTS := ArcherC20v4