[media] v4l: Add subdev sensor g_skip_frames operation

Some buggy sensors generate corrupt frames when the stream is started.
This new operation return the number of corrupt frames to skip when
starting the stream.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

include/media/v4l2-subdev.h

@@ -341,9 +341,13 @@ struct v4l2_subdev_vbi_ops {
  *		      This is needed for some sensors, which always corrupt
  *		      several top lines of the output image, or which send their
  *		      metadata in them.
+ * @g_skip_frames: number of frames to skip at stream start. This is needed for
+ *		   buggy sensors that generate faulty frames when they are
+ *		   turned on.
  */
 struct v4l2_subdev_sensor_ops {
 	int (*g_skip_top_lines)(struct v4l2_subdev *sd, u32 *lines);
+	int (*g_skip_frames)(struct v4l2_subdev *sd, u32 *frames);
 };
 
 /*