ath79: Add support for MOXA AWK-1137C

ath79: Add support for MOXA AWK-1137C

Device specifications:
======================

* Qualcomm/Atheros AR9344
* 128 MB of RAM
* 16 MB of SPI NOR flash
* 2x 10/100 Mbps Ethernet
* 2T2R 2.4/5 GHz Wi-Fi
* 4x GPIO-LEDs (1x wifi, 2x ethernet, 1x power)
* 1x GPIO-button (reset)
* 2x fast ethernet
  - lan1
    + builtin switch port 1
    + used as WAN interface
  - lan2
    + builtin switch port 2
    + used as LAN interface
* 9-30V DC
* external antennas

Flashing instructions:
======================

Log in to https://192.168.127.253/
   Username: admin
   Password: moxa

Open Maintenance > Firmware Upgrade and install the factory image.

Serial console access:
======================

Connect a RS232-USB converter to the maintenance port.
   Pinout: (reset button left) [GND] [NC] [RX] [TX]

Firmware Recovery:
==================

When the WLAN and SYS LEDs are flashing, the device is in recovery mode.

Serial console access is required to proceed with recovery.

Download the original image from MOXA and rename it to 'awk-1137c.rom'.
Set up a TFTP server at 192.168.127.1 and connect to a lan port.

Follow the instructions on the serial console to start the recovery.

Signed-off-by: Maximilian Martin <mm@simonwunderlich.de>