[media] coda: make seq_end_work optional

In preparation for CODA9 JPEG support, which doesn't have to call
SEQ_END on the BIT processor.

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>