media: chips-media: wave5: Add support for background detection

media: chips-media: wave5: Add support for background detection

Implement V4L2_CID_MPEG_VIDEO_BACKGROUND_DETECTION in the Wave5 encoder
driver. When enabled, the hardware detects background regions in a frame
and uses fewer bits or skip mode to encode them, reducing bitrate for
streams with stationary scenes.

Signed-off-by: Jackson Lee <jackson.lee@chipsnmedia.com>
Signed-off-by: Nas Chung <nas.chung@chipsnmedia.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>