The Sipeed Longan SoM 3H is a system on module based on the Allwinner
H618 SoC. The SoM features:

- Four ARM Cortex-A53 cores, Mali-G31 MP2 GPU
- 2/4 GiB LPDDR4 DRAM SoMs
- AXP313a PMIC
- eMMC

The Sipeed Longan PI 3H is a development board based on the above SoM.
The board features:
- Longan SoM 3H
- Raspberry-Pi-1 compatible GPIO header
- 2 USB 2.0 host port
- 1 USB 2.0 type C port (power supply + OTG)
- MicroSD slot
- 1Gbps Ethernet port (via RTL8211 PHY)
- HDMI port
- WiFi/BT chip

Add the devicetree file describing the currently supported features,
namely PMIC, LEDs, UART, SD card, eMMC, USB and Ethernet.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20240211081739.395-3-jszhang@kernel.orgSigned-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>