media: dt-bindings: media: rockchip-vpu: Add PX30 compatible

The Rockchip PX30 SoC has a Hantro VPU that features a decoder (VDPU2)
and an encoder (VEPU2).

Suggested-by: Alex Bee <knaerzche@gmail.com>
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>