dt-bindings: arm: rockchip: Add PinePhone Pro bindings

Document board compatible names for Pine64 PinePhonePro.

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



Signed-off-by: Tom Fitzhenry <tom@tom-fitzhenry.me.uk>
Reviewed-by: Caleb Connolly <kc@postmarketos.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220815123004.252014-2-tom@tom-fitzhenry.me.uk


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