ath79: add support for TP-Link TL-WPA8630 v1

ath79: add support for TP-Link TL-WPA8630 v1

This ports the TP-Link TL-WPA8630 v1 from ar71xx to ath79.

Specifications:

SoC: QCA9563
CPU: 750 MHz
Flash/RAM: 8 / 128 MiB
Ethernet: 3x 1G ports (QCA8337 switch)
WLAN: 2.4 GHz b/g/n, 5 GHz a/n/ac (ath10k)

Buttons, LEDs and network setup appear to be almost identical
to the v2 revision.

Powerline interface is connected to switch port 5 (Label LAN4).

Installation:

No "fresh" device was available for testing the factory image.

It is not known whether flashing via OEM firmware GUI is possible
or not. A discussion from 2018 [1] about that indicates a few
adjustments are necessary, but it is not clear whether those
are already implemented with the TPLINK_HEADER_VERSION = 2 or not.

Note that for the TL-WPA8630P v1, the TPLINK_HWID needs to be
changed to 0x86310001 to allow factory flashing.

[1] https://forum.openwrt.org/t/solved-tl-wpa8630p-lede-does-not-install/8161/27

Recovery:

Recovery is only possible via serial.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>