Mapping multi-plane surfaces won't work correctly without driver
supporting PIPE_VIDEO_CAP_SUPPORTS_CONTIGUOUS_PLANES_MAP.
Remove the check for ffmpeg process and instead check for
multi-plane format and driver support only.
Reviewed-by: Leo Liu <leo.liu@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24381>