ath79: add support for COMFAST CF-E110N

ath79: add support for COMFAST CF-E110N

This patch adds support for the COMFAST CF-E110N, an outdoor wireless
CPE with two Ethernet ports and a 802.11bgn radio.

Specifications:

 - 650/400/216 MHz (CPU/DDR/AHB)
 - 2x 10/100 Mbps Ethernet, both with PoE-in support
 - 64 MB of RAM (DDR2)
 - 16 MB of FLASH
 - 2T2R 2.4 GHz, up to 26 dBm
 - 11 dBi built-in antenna
 - POWER/LAN/WAN/WLAN green LEDs
 - 4x RSSI LEDs (2x red, 2x green)
 - UART (115200 8N1) and GPIO (J9) headers on PCB

Flashing instructions:

 The original firmware is based on OpenWrt so a sysupgrade image can be
 installed via the stock web GUI. Settings from the original firmware
 will be saved and restored on the new want, so a factory reset will be
 needed: once the new firmware is flashed, perform the factory reset by
 pushing the reset button several times during the boot process, while the
 WAN LED flashes, until it starts flashing quicker.

 The U-boot bootloader contains a recovery HTTP server to upload the
 firmware. Push the reset button while powering the device on and keep it
 pressed for >10 seconds. The recovery page will be at http://192.168.1.1

Notes:

 The device is advertised, sold and labeled as "CF-E110N", but the
 bootloader and the stock firmware identify it as "v2".

Acknowledgments:

 Petr Štetiar <ynezz@true.cz>
 Sebastian Kemper <sebastian_ml@gmx.net>
 Chuanhong Guo <gch981213@gmail.com>

Signed-off-by: Roger Pueyo Centelles <roger.pueyo@guifi.net>
[drop unused labels from devicetree source file]
Signed-off-by: Mathias Kresin <dev@kresin.me>