mediatek: filogic: add support for ASUS TUF-AX4200Q

mediatek: filogic: add support for ASUS TUF-AX4200Q

ASUS TUF-AX4200Q(TUF 小旋风Pro WiFi6 AX4200) is a home router that adds an additional 2.5G Ethernet port to ASUS TUF-AX4200.

Hardware
- - - - - - - -
- SOC   : MediaTek MT7986
- RAM   : 512MB DDR3
- FLASH : 256MB SPI-NAND (Winbond W25N02KV)
- WIFI  : Mediatek MT7986 DBDC 802.11ax 2.4/5 GHz
- ETH   : MediaTek MT7531 Switch
          MaxLinear GPY211C 2.5 N-Base-T PHY (WAN)
          MaxLinear GPY211C 2.5 N-Base-T PHY (LAN)
- UART  : 3V3 115200 8N1 (Pinout silkscreened / Do not ocnnect VCC)

Installation
- - - - - - - -
Vendor-UI Method:

1. Download or make the OpenWrt initramfs.trx image
2. Connect the PC via LAN to one of the yellow router ports and wait until your PC to get a DHCP lease.
3. Browse to http://192.168.50.1/
4. If your router is brand new, finish the setup process and log into the Web-UI.
5. Navigate to Administration -> Firmware Upgrade and upload the downloaded OpenWrt image.
6. Wait for OpenWrt to boot. Transfer the sysupgrade image to the device using SCP and install using sysupgrade.

   $ sysupgrade -n <path-to-sysupgrade.bin>

TFTP Method:

1. Download the OpenWrt initramfs image.
   Copy the image to a TFTP server reachable at 192.168.1.70/24.
   Rename the image to tufax4200q.bin.

2. Connect the PC with TFTP server to the TUF-AX4200Q.
   Set a static ip on the ethernet interface of your PC.
   (IP address: 192.168.1.70, subnet mask: 255.255.255.0)
   Connect to the serial console,
   interrupt the autoboot process by pressing '4' when prompted.

3. Download & Boot the OpenWrt initramfs image.

   $ setenv ipaddr 192.168.1.1
   $ setenv serverip 192.168.1.70
   $ tftpboot 0x46000000 tufax4200q.bin
   $ bootm 0x46000000

4. Wait for OpenWrt to boot.
   Transfer the sysupgrade image to the device using SCP and install using sysupgrade.

   $ sysupgrade -n <path-to-sysupgrade.bin>

(based on support for ASUS RT-AX52 by achterin and trx image generation by remittor)

Link: https://github.com/openwrt/openwrt/pull/20900
(cherry picked from commit e7086d7a2fc00410df079b4897a47a823a36068d)
Signed-off-by: Brian Lee <larte332@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/21036
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>