arm64: dts: allwinner: h616: Add OrangePi Zero 3 board support

The OrangePi Zero 3 is a development board based on the Allwinner H618 SoC,
which seems to be just an H616 with more L2 cache. The board itself is a
slightly updated version of the Orange Pi Zero 2. It features:
- Four ARM Cortex-A53 cores, Mali-G31 MP2 GPU
- 1/1.5/2/4 GiB LPDDR4 DRAM SKUs (only up to 1GB on the Zero2)
- AXP313a PMIC (more capable AXP305 on the Zero2)
- Raspberry-Pi-1 compatible GPIO header
- extra 13 pin expansion header, exposing pins for 2x USB 2.0 ports
- 1 USB 2.0 host port
- 1 USB 2.0 type C port (power supply + OTG)
- MicroSD slot
- on-board 16MiB bootable SPI NOR flash (only 2MB on the Zero2)
- 1Gbps Ethernet port (via Motorcomm YT8531 PHY) (RTL8211 on the Zero2)
- micro-HDMI port
- (yet) unsupported Allwinner WiFi/BT chip

Add the devicetree file describing the currently supported features,
namely LEDs, SD card, PMIC, SPI flash, USB. Ethernet seems unstable at
the moment, though the basic functionality works.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20230804170856.1237202-4-andre.przywara@arm.com


Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>