arm64: dts: rockchip: Add initial support for Pine64 PinePhone Pro

This is a basic DT containing regulators and UART, intended to be a
base that myself and others can add additional nodes in future patches.

Tested to work: booting from eMMC/SD, output over UART.

https://wiki.pine64.org/wiki/PinePhone_Pro

This is derived from the community pine64-org repo[0] with fixes from
https://megous.com/git/linux.

0. https://gitlab.com/pine64-org/linux/-/commit/261d3b5f8ac503f97da810986d1d6422430c8531



Signed-off-by: Martijn Braam <martijn@brixit.nl>
Co-developed-by: Kamil Trzciński <ayufan@ayufan.eu>
[no SoB, but Kamil is happy for this patch to be submitted]
Co-developed-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Ondrej Jirman <megi@xff.cz>
Co-developed-by: Tom Fitzhenry <tom@tom-fitzhenry.me.uk>
Signed-off-by: Tom Fitzhenry <tom@tom-fitzhenry.me.uk>
Reviewed-by: Caleb Connolly <kc@postmarketos.org>
Reviewed-by: Nícolas F. R. A. Prado <n@nfraprado.net>
Tested-by: Nícolas F. R. A. Prado <n@nfraprado.net>
Link: https://lore.kernel.org/r/20220829050040.17330-2-tom@tom-fitzhenry.me.uk


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