media: vb2-core: vb2_buffer_done: consolidate docs

Documentation about what start_streaming() should do on failure are
scattered in two places and mostly duplicated, so consolidate them in
one of the two places.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Pawel Osciak <pawel@osciak.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

include/media/videobuf2-core.h

@@ -602,9 +602,7 @@ void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
  *		Either %VB2_BUF_STATE_DONE if the operation finished
  *		successfully, %VB2_BUF_STATE_ERROR if the operation finished
  *		with an error or %VB2_BUF_STATE_QUEUED if the driver wants to
- *		requeue buffers. If start_streaming fails then it should return
- *		buffers with state %VB2_BUF_STATE_QUEUED to put them back into
- *		the queue.
+ *		requeue buffers.
  *
  * This function should be called by the driver after a hardware operation on
  * a buffer is finished and the buffer may be returned to userspace. The driver
@@ -613,9 +611,9 @@ void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
  * to the driver by &vb2_ops->buf_queue can be passed to this function.
  *
  * While streaming a buffer can only be returned in state DONE or ERROR.
- * The start_streaming op can also return them in case the DMA engine cannot
- * be started for some reason. In that case the buffers should be returned with
- * state QUEUED.
+ * The &vb2_ops->start_streaming op can also return them in case the DMA engine
+ * cannot be started for some reason. In that case the buffers should be
+ * returned with state QUEUED to put them back into the queue.
  */
 void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);