media: coda: mark the last output buffer on decoder stop command

Mark the last output buffer to be decoded and only copy pending queued
output buffers into the bitstream ring buffer in the BIT processor
decoder case.

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>