ath79: add support for COMFAST CF-E380AC v2

ath79: add support for COMFAST CF-E380AC v2

COMFAST CF-E380AC v2 is a ceiling mount AP with PoE
support, based on Qualcomm/Atheros QCA9558+QCA9880+AR8035.

There are two versions of this model, with different RAM
and U-Boot mtd partition sizes:
- v1: 128 MB of RAM, 128 KB U-Boot image size
- v2: 256 MB of RAM, 256 KB U-Boot image size

Version number is available only inside vendor GUI,
hardware and markings are the same.

Short specification:

- 720/600/200 MHz (CPU/DDR/AHB)
- 1x 10/100/1000 Mbps Ethernet, with PoE support
- 128 or 256 MB of RAM (DDR2)
- 16 MB of FLASH
- 3T3R 2.4 GHz, with external PA (SE2576L), up to 28 dBm
- 3T3R 5 GHz, with external PA (SE5003L1), up to 30 dBm
- 6x internal antennas
- 1x RGB LED, 1x button
- UART (T11), LEDs/GPIO (J7) and USB (T12) headers on PCB
- external watchdog (Pericon Technology PT7A7514)

COMFAST MAC addresses :
Though the OEM firmware has four adresses in the usual locations,
it appears that the assigned addresses are just incremented in a different way:

Interface    address    location
Lan              *:00           0x0
2.4g             *:0A           n/a (0x0 + 10)
5g               *:02           0x6

Unused Addresses found in ART hexdump
address    location
*:01           0x1002
*:03           0x5006

To keep code consistency the MAC address assignments are made based on increments of the one found in 0x0;

Signed-off-by: Joao Henrique Albuquerque <joaohccalbu@gmail.com>