mediatek/filogic: add support for Cudy AP3000 v1

mediatek/filogic: add support for Cudy AP3000 v1

Hardware:
  SoC:     MT7981b
  RAM:     512 MB
  Flash:   256 MB SPI NAND
  Ethernet:
    1x2.5Gbps (rtl8221b)
  WiFi:    2x2 MT7981
  Button:  Reset
  LED:     1x multicolor

Installation
------------
At the moment, firmware installation is only possible via a transition firmware.
It's can be requested from the manufacturer by email to [email protected]

Signed-off-by: Maxim Anisimov <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/17225
Signed-off-by: Hauke Mehrtens <[email protected]>