[media] coda: move meta out of padding

Handle an empty buffer metadata list without crashing. This can happen
if the decoder is fed a broken stream, or multiple compressed frames in
a single queued buffer.

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>