media: coda: only wake up capture queue if no pending buffers to encode

If there are no pending queued output buffers to be encoded, waking up
the capture queue with -EPIPE signals end of stream. If there are
pending buffers on the other hand, setting the V4L2_BUF_FLAG_LAST on
the resulting encoded capture buffers is all that is needed.

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>