[media] coda: increase frame stride to 16 for h.264

When encoding into h.264, the input frame stride needs to be a multiple of 16.
During allocation of the input buffers, it may not be known yet whether the
encoder should create h.264 or not. Assume the worst and always use a frame
stride that is a multiple of 16.

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