arm64: dts: rockchip: add px30-pp1516 base dtsi and board variants

PP1516 are Touchscreen devices built around the PX30 SoC and companion
devices to PX30-Cobra, again with multiple display options.

The devices feature an EMMC, OTG port and a 720x1280 display with a
touchscreen and camera

Signed-off-by: Heiko Stuebner <heiko.stuebner@cherry.de>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Link: https://lore.kernel.org/r/20250514150745.2437804-7-heiko@sntech.de


Signed-off-by: Heiko Stuebner <heiko@sntech.de>