mediatek/filogic: add support for COMFAST CF-XR186

mediatek/filogic: add support for COMFAST CF-XR186

The COMFAST CF-XR186 is a WiFi repeater. The original OEM firmware is a
fork of OpenWrt 21.02.

To replace the OEM firmware with OpenWrt, flash the sysupgrade image
through the firmware upgrade option via the OEM firmware's web UI.
The OEM firmware upgrade page does not provide an option to perform a
factory reset, so after the flash completes and the device reboots,
perform a reset by holding in the WPS/Reset button until the WiFi
LED flashes red.

The led-boot, led-failsafe, led-upgrade, and led-running aliases all
point at the red WLAN GPIO LED.

The green and blue WLAN GPIO LEDs are used to indicate activity on the
2.4GHz and 5GHz radios. 01_leds assigns netdev triggers for those LEDs
to phy0-ap0 and phy1-ap0 respectively; if neither AP interface exists
(e.g. station-only repeater setups), both LEDs stay dark even when WiFi
traffic is flowing.

Specifications:
- SoC: MediaTek MT7981B
- RAM: 256MB
- Flash: SPI NAND
- WiFi: 2.4GHz + 5GHz (AX3000, 4x 3dBi antennas)
- Ethernet: 1x 10/100/1000M
- LEDs: power (not controllable), blue Ethernet, blue/green/red WiFi
- Button: WPS/Reset
- Power: 100-240V AC (wall plug)
- UART: 115200 8N1

MAC Addresses:
- LAN   : 40:A5:EF:xx:xx:2D (Factory, 0xe000)
- 2.4GHz: 40:A5:EF:xx:xx:2F (Factory, 0x0004)
- 5GHz  : 40:A5:EF:xx:xx:30 (Factory, 0x8000)

Signed-off-by: David Berdik <dgberdik@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22471
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>