media: vivid: drop v4l2_ctrl_request_complete() from start_streaming

If start_streaming() fails and all queued buffers are returned to
vb2, then do not call v4l2_ctrl_request_complete(). Nothing happened
to the request and the state should remain as it was before
start_streaming was called.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>