v4l2-core: Round up in clamp_align

In most use cases, it's easyer to deal with a larger size and crop it,
then a smaller video size.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
s5p-mfc: Only export formats actually supported

HW revisions of the MFC has slightly different formats supported. This
patch ensure only supported format are listed when enumarating formats.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>