mediatek-filogic: remove broken flag for TUF AX4200 (#3064)

There is a new way to flash OpenWrt on the ASUS TUF AX4200 which does
not require to open the device.

Link: https://github.com/blocktrron/openwrt-asus-filogic-factory/releases/tag/filogic-v1



Signed-off-by: David Bauer <mail@david-bauer.net>