arm64: dts: rockchip: add csi-dphy to px30

Add the CSI dphy node to the core px30 devicetree for later use
with the rkisp.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Link: https://lore.kernel.org/r/20210722073955.1192168-1-heiko@sntech.de


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