arm64: dts: rockchip: Add devicetree for Pine64 PineTab2

This includes support for both the v0.1 units that were sent to developers and
the v2.0 units from production.

v1.0 is not included as no units are known to exist.

Working/Tested:
- SDMMC
- UART
- Buttons
- Charging/Battery/PMIC
- Audio
- USB
- Display
- SPI NOR Flash

Signed-off-by: Alexander Warnecke <awarnecke002@hotmail.com>
Signed-off-by: Manuel Traut <manut@mecka.net>
Tested-By: Diederik de Haas <didi.debian@cknow.org>
Reviewed-by: Ondrej Jirman <megi@xff.cz>
Tested-by: Ondrej Jirman <megi@xff.cz>
Link: https://lore.kernel.org/r/20240127-pinetab2-v4-4-37aab1c39194@mecka.net
Signed-off-by: Heiko Stuebner <heiko@sntech.de>