arm64: dts: rockchip: Add gpu opp nodes to px30 dtsi

This matches the values in the vendor kernel.

Signed-off-by: Maciej Matuszczyk <maccraft123mc@gmail.com>
[added tiny commit description]
Link: https://lore.kernel.org/r/20210225081943.127714-1-maccraft123mc@gmail.com


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