ramips: add support for TP-Link Archer MR200v5

ramips: add support for TP-Link Archer MR200v5

Specifications:
	CPU:     MT7628AN 580MHz
	RAM:     64MB DDR2
	FLASH:   8MB EN25QH64 NOR SPI
	WIFI:    2.4GHz 2x2 MT7628 b/g/n internal
	WIFI:    5GHz 1x1 MT7610E ac/n PCI
	LTE:     Qualcomm MDM9207
	ETH:     4xLAN 100base-T integrated
	SWITCH:  RT3050-ESW Port 0,1,2,3: LAN, Port 6: CPU
	LEDS:    LAN, WAN, Power, 3x signal strength, WiFi
	BTNS:    Reset, WiFi toggle
	UART:    Near ETH ports, Vcc-GND-RX-TX, 115200, 8N1

Installation:
	1. Update using recovery mode
        - set your IP to 192.168.0.225, subnet mask: 255.255.255.0
        - start tftp server, rename tftp-recovery.bin to
          tp_recovery.bin and place it into the server's directory
        - while holdig the "reset" button, power on the device
        - keep holding "reset" until the file is being transferred

Notes:
	This board has only one MAC address programmed
        in the "romfile" partition:
        - MAC for phy0 (2.4GHz) at romfile 0xf100 (0)
        - MAC for phy1 (5GHz) at romfile 0xf100 (-1)
        - stock firmware re-uses phy0 MAC for ethernet
        - stock firmware uses romfile 0xf100 (1) for WWAN;
          not used since QMI interface is raw IP

Signed-off-by: Lea Teuberth <lea.teuberth@outlook.com>