media: staging: dt-bindings: add Rockchip MIPI RX D-PHY RX0 yaml bindings

Add yaml DT bindings for Rockchip MIPI D-PHY RX

This was tested and verified with:
mv drivers/staging/media/phy-rockchip-dphy-rx0/Documentation/devicetree/bindings/phy/rockchip-mipi-dphy-rx0.yaml  Documentation/devicetree/bindings/phy/
make dt_binding_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/phy/rockchip-mipi-dphy-rx0.yaml
make dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/phy/rockchip-mipi-dphy-rx0.yaml

Signed-off-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>