arm64: dts: allwinner: h616: Add X96 Mate TV box support

The X96 Mate is an Allwinner H616 based TV box, featuring:
  - Four ARM Cortex-A53 cores, Mali-G31 MP2 GPU
  - 2GiB/4GiB RAM (fully usable!)
  - 16/32/64GiB eMMC
  - 100Mbps Ethernet (via embedded AC200 EPHY, not yet supported)
  - Unsupported Allwinner WiFi chip
  - 2 x USB 2.0 host ports
  - HDMI port
  - IR receiver
  - 5V/2A DC power supply via barrel plug

Add a basic devicetree for it, with SD card and eMMC working, as
well as serial and the essential peripherals, like the AXP PMIC.

This DT is somewhat minimal, and should work on many other similar TV
boxes with the Allwinner H616 chip.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220708105235.3983266-8-andre.przywara@arm.com