mediatek: filogic: Add support for Wavlink WL-WN586X3

mediatek: filogic: Add support for Wavlink WL-WN586X3

Hardware
--------
- SOC: MediaTek MT7981
- ram: 256MB DDR3
- FLASH: 16MB SPI-NOR
- Ethernet: 2x1Gb Lan 1x1Gb Wan
- WIFI: MediaTek MT7981 2x2 DBDC 802.11ax 2T2R (2.4/5)
- LEDs: 2xLan 1x Wan 1x WIFI 1xSTATUS

MAC table, same as stock firmware:
LAN: 80:3F:5D:xx:xx:x1 partition "hw" at 0x44e (ASCII)
WAN: 80:3F:5D:xx:xx:x2 partition "hw" at 0x460 (ASCII)
 2G: 80:3F:5D:xx:xx:x3 partition "factory" at 0x4 (binary), on label
 5G: 80:3F:5D:xx:xx:x3 Same as 2G

Installation Method 1: ssh
--------------------------
1. Connect PC to the lan port. Set the PC IP to 192.168.10.100 if
   required.
2. Navigate to http://192.168.10.1/
3. Log into the Wavlink WebGUI. Default username/password is
   admin/admin.
4. Use WebGUI to upgrade the firmware to
   WAVLINK_WN586X3-A_M86X3A_V240113_WO-GDBYFM-modified.bin
   downloaded from
   https://github.com/themaverickdm/firmware-misc/tree/main/wavlink/wl-wn586x3
   Warning: All settings will be lost!
5. Wait about 5 minutes, and after flashing is completed, log into
   the router using (with admin123 as password):
   ssh root@192.168.10.1
6. scp the openwrt image file onto the router, usually under /tmp
   somewhere.
   openwrt-mediatek-filogic-wavlink_wl-wn586x3-squashfs-sysupgrade.bin
7. Flash openwrt image file like so:
   mtd write \
     openwrt-mediatek-filogic-wavlink_wl-wn586x3-squashfs-sysupgrade.bin \
     firmware
   Warning: Previous firmware will be overwritten!
8. Wait about 5 minutes, and after the flashing is completed, set
   the PC IP to 192.168.1.100 if required and log into the router
   like so:
   ssh root@192.168.1.1

Installation Method 2: u-boot
-----------------------------
1. Connect UART:  TX-> 586X3 RX, RX-> 586X3 TX, GND-> 586 GND.
2. Connect PC to the wan (not lan!) port.
3. Setup the tftp server on PC, set IP to 192.168.10.100,
4. Power on the device. Select '2' to upgrade firmware in Uboot.
5. Input the image name and start to upgrade.

Uboot console log:

CPU:   MediaTek MT7981
Model: mt7981-rfb
DRAM:  256 MiB
Core:  34 devices, 13 uclasses, devicetree: embed
Loading Environment from nowhere... OK
In:    serial@11002000
Out:   serial@11002000
Err:   serial@11002000
Net:
Warning: ethernet@15100000 (eth0) using random MAC address -
02:47:fb:b2:53:2d
eth0: ethernet@15100000
UBOOT WN586X3A
gpio: pin 9 (gpio 9) value is 0
gpio: pin 10 (gpio 10) value is 0
gpio: pin 5 (gpio 5) value is 0
gpio: pin 12 (gpio 12) value is 0
gpio: pin 13 (gpio 13) value is 0

  *** U-Boot Boot Menu ***

      1. Startup system (Default)
      2. Upgrade firmware
      3. Upgrade ATF BL2
      4. Upgrade ATF FIP
      5. Upgrade single image
      6. Load image
      0. U-Boot console

Co-authored-by: R Maru <deviantmaru@gmail.com>
Signed-off-by: R Maru <deviantmaru@gmail.com>
Signed-off-by: Sijia Huang <engineer31@win-star.com>