media: vicodec: add V4L2_CID_MIN_BUFFERS_FOR_OUTPUT

The stateful encoder requires the presence of this control.
Since a single buffer is sufficient for vicodec, we just
set this control to 1.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>