media: coda: round up frame sizes to multiples of 16 for MPEG-4 decoder

We need internal frames to be rounded up to full macroblocks for MPEG-4
decoding as well.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>