[media] media: coda: Fix H.264 header alignment

Length of H.264 headers is variable and thus it might not be
aligned for the coda to append the encoded frame. This causes
the first frame to overwrite part of the H.264 PPS.
In order to solve that, a filler NAL must be added between
the headers and the first frame to preserve alignment.

[mchehab@redhat.com: Fix a few CodingStyle issues]
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>