The Rockchip VOP2 features an internal RGB output block, which can be
attached any video port of the VOP2. Add support for this output block.

Signed-off-by: Michael Riesch <michael.riesch@wolfvision.net>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230124054706.3921383-6-michael.riesch@wolfvision.net