[media] coda: Set last buffer flag and fix EOS event

Setting the last buffer flag causes the videobuf2 core to return -EPIPE from
DQBUF calls on the capture queue after the last buffer is dequeued.
This patch also fixes the EOS event to conform to the specification. It now is
sent right after the last buffer has been decoded instead of when the last
buffer is dequeued.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>