media: vb2: core: Finish buffers at the end of the stream

If buffers were prepared or queued and the buffers were released without
starting the queue, the finish mem op (corresponding to the prepare mem
op) was never called to the buffers.

Before commit a136f59c there was no need to do this as in such a case
the prepare mem op had not been called yet. Address the problem by
explicitly calling finish mem op when the queue is stopped if the buffer
is in either prepared or queued state.

Fixes: a136f59c ("[media] vb2: Move buffer cache synchronisation to prepare from queue")

Cc: stable@vger.kernel.org # for v4.13 and up
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>