media: coda: mark last pending buffer or last meta on decoder stop command

If there is still a buffer pending, mark it as the last buffer. It will
create a meta that is flagged as last when the buffer is copied into the
bitstream ring buffer. If there are no more buffers pending, find the
last bitstream meta and mark it as last. If there is no bitstream meta
either, wake up the capture queue as there will be no more decoded
frames.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>