arm64: dts: rockchip: add support for Powkiddy RGB30

arm64: dts: rockchip: add support for Powkiddy RGB30

The Powkiddy RGB30 is a portable game device based on the Rockchip
RK3566 SoC. It has GPIO buttons on the face and sides for input, stereo
speakers, a 720x720 4 inch DSI display, a USB-C host port and a USB-C
peripheral port, dual SD card slots, WiFi, Bluetooth, and 1GB of RAM.

Working/Tested:
- SDMMC
- UART (for debugging)
- Buttons
- Charging/battery/PMIC
- Speaker/Headphones
- USB
- WiFi
- Bluetooth
- Display (at 59.04hz)

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20231013183918.225666-6-macroalpha82@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>