mediatek: filogic: add support for COMFAST CF-WA933

mediatek: filogic: add support for COMFAST CF-WA933

The Comfast CF-WA933[1] is an outdoor dual-band WiFi 6 access
point/router. They also OEM their routers for other providers. This PR
adds support based on, and substantially updates, the downstream device
definition[2] from Wayru, one such white label client.

It can be powered by a 12V DC barrel jack (standard 5.5x2.5mm, center
positive) or via 802.3af POE.

Hardware summary:
- SoC: MediaTek MT7981A
- RAM: 256 MiB
- Flash: SPI-NAND 128 MiB (Factory uses 64M; see details below to use
  the full 128M!)
- WiFi (MT7976DA): dual-band 802.11ax
- Ethernet (MT7531AE): 3x gigabit: 1x WAN + 2x LAN (labeled lan1/lan2).
- Button: reset
- LEDs: Power (always on), WLAN, WAN, LAN1, LAN2
- Serial: Internal header (Four unpopulated headers, clearly labeled)

MAC addresses on the tested unit:
- Label:   40:a5:ef:f0:5e:0f
- LAN:     40:a5:ef:f0:5e:0f  Factory 0xe000
- WAN:     40:a5:ef:f0:5e:10  Factory 0xe000 + 1
- 2.4 GHz: 40:a5:ef:f0:5e:11  Factory 0x0004
- 5 GHz:   40:a5:ef:f0:5e:13  Factory 0x8000 + 1

The serial number is stored as an ASCII string at Factory 0xe100.

Disassembly:

Unscrew the six 3mm hex bolts on the dome and the six 5mm bolts on the
side of the arm, then lift the dome. For reassembly, make sure the large
O ring is in the groove in the dome.

OpenWrt installation:

1. Connect to Ethernet on the WAN port. Manually set your IP address to
192.168.1.10 (important!)
2. Upload the OpenWrt sysupgrade image at http://192.168.1.1

The default U-Boot partition layout does not expose the full flash
capacity. Change the mtdparts U-Boot environment variable before
rebooting and then installing the image for the 128 MiB variant through
the same bootloader recovery/upgrade page.

Method 1: Using the serial console

1. Disassemble the unit and connect to the serial console (115200 8N1).
   Leave 3.3V disconnected.
2. On the boot loader, go straight to "0. U-Boot console"
3. Then enter:
   setenv mtdparts 'nmbm0:1024k(bl2),512k(u-boot-env),2048k(factory),2048k(fip),117248k(ubi)'
   saveenv
   reset

Method 2: From OpenWrt using uboot-envtools

apk add uboot-envtools
fw_setenv mtdparts 'nmbm0:1024k(bl2),512k(u-boot-env),2048k(factory),2048k(fip),117248k(ubi)'
reboot

Return to vendor firmware:
1. If you have changed the mtdparts environment variable, undo the
   change by setting:
   mtdparts 'nmbm0:1024k(bl2),512k(u-boot-env),2048k(factory),2048k(fip),65536k(ubi)'
2. Re-enter the same bootloader recovery/upgrade page.
3. Upload a stock COMFAST firmware image, e.g. from
   http://www.comfast.com.cn/index.php?m=content&c=index&a=show&catid=85&id=773

[1]: https://comfastgroup.com/product/cf-wa933/
[2]: https://github.com/Wayru-Network/wayru-os/tree/main/profiles/prometheus

Signed-off-by: Guillaume RISCHARD <git@stereo.lu>
Link: https://github.com/openwrt/openwrt/pull/22379
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>