mediatek: filogic: add support for TP-LINK BE450

mediatek: filogic: add support for TP-LINK BE450

This commit adds support for TP-LINK BE450.

Device specification
--------------------
SoC Type:   MediaTek MT7988D, Cortex-A73, 64-bit
RAM:        512MB
Flash:      SPI NAND GigaDevice (128 MiB)
Ethernet:   MediaTek MT7531AE (3 Ports) + 2.5GbE (internal MT7988 phy) + 10GbE (RTL8261N)

WLAN:       MT7992
WLAN 2g:    MediaTek MT7975N, b/g/n/ax/be, MIMO 4x4
WLAN 5g:    MediaTek MT7979N, a/n/ac/ax/be, MIMO 4x4
LEDs:       8 LEDs, 1 status blue, 2x WIFI blue, 2x Internet
	        blue/orange, 1 LAN blue, 1 usb blue, 1 wps blue, gpio-controlled
Button:     2 (Reset, WPS)
USB port:   Yes
Power:      12 VDC, 2 A
Connector:  Barrel
Bootloader: Main U-Boot - U-Boot 2023.10-rc4. Additionally, ubi0
            partition contain "seconduboot" (also U-Boot 2023.10-rc4)

Serial console (UART), unpopulated, located near the power connector
---------------------
heatsink
|   |
|   |
|   |     +----+-----+------+-------+               +-----------------+
|   |     | TX |  RX |  GND | +3.3V |               | power connector |
+---+     +----+-----+------+-------+               +-----------------+
                                  |
                Don't connect ----+

Disassemble: rm the 2 screws at the bottom and the one at the backside.
             un-clip the case starting at the edge above the LEDs.

Installation (UART)
-------------------
1. Place OpenWrt initramfs image on tftp server with IP 192.168.1.2
2. Attach UART, switch on the router and interrupt the boot process by
   pressing 'Ctrl-C'
3. Load and run OpenWrt initramfs image:
      tftpboot 0x50000000 openwrt-mediatek-filogic-tplink_be450-initramfs-kernel.bin && bootm 0x50000000
4. Run 'sysupgrade -n' with the sysupgrade OpenWrt image

Note: the 10GbE (RTL8261N) is only working if reverting this Realtek target specific commit:
      https://github.com/openwrt/openwrt/commit/b77fa45d1278443d534919598c0301719fed2784

      The second ubi partition (ubi1) is empty and there is no known
      dual-partition mechanism, neither in u-boot nor in the stock firmware.

      NMBM is not used.

Not Working: WED, if activated, MT7992 isn't recognized any more.

Signed-off-by: Dirk Buchwalder <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20398
Signed-off-by: Hauke Mehrtens <[email protected]>