arm64: dts: meson-g12b-gtking-pro: add initial device-tree

The Shenzen AZW (Beelink) GT-King Pro is based on the Amlogic W400
reference board with an S922X chip.

- 4GB LPDDR4 RAM
- 64GB eMMC storage
- 10/100/1000 Base-T Ethernet
- AP6356S Wireless (802.11 a/b/g/n/ac, BT 4.1)
- HDMI 2.1 video
- Analogue audio output
- 1x RS232 port
- 2x USB 2.0 port
- 2x USB 3.0 ports
- IR receiver
- 1x micro SD card slot
- 1x Power on/off button

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20200520014329.12469-6-christianshewitt@gmail.com