mediatek: filogic: add Netcore N60 Pro support

mediatek: filogic: add Netcore N60 Pro support

Hardware specification:
SoC: MediaTek MT7986A 4x A53
Flash: ESMT F50L1G41LB 128MB
RAM: M16U4G16256A DDR4 512MB
Ethernet: 2x 2.5G + 3x 1G
USB: 1x USB 3.0
WiFi1: MT7975N 2.4GHz 4T4R
WiFi2: MT7975PN 5GHz 4T4R
Button: Reset, WPS
Power: DC 12V 2A

Flash instructions:

    Connect to the router using ssh or telnet,
    username: useradmin, password is the web
    login password of the router.
    Use scp to upload bl31-uboot.fip and flash:
    "mtd write xxx-bl31-uboot.fip FIP"
    "mtd erase ubi"
    Connect to the router via the Lan port,
    set a static ip of your PC.
    (ip 192.168.1.254, gateway 192.168.1.1)
    Download initramfs image, reboot router,
    waiting for tftp recovery to complete.
    After openwrt boots up, perform sysupgrade.

Note:

    Back up all mtd partitions before flashing.

Signed-off-by: Yujie Zhu <libriunc@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/18138
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>