arm64: dts: rockchip: add basic dts for Pine64 Quartz64-A

Add a basic dts for the Pine64 Quartz64 Model A Single Board Computer.
This board outputs on uart2 for debug.

Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210710151034.32857-5-pgwipeout@gmail.com


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