[media] videodev2.h: Make V4L2_PIX_FMT_MPEG4 comment more specific about its usage

Signed-off-by: Ismael Luceno <ismael.luceno@corp.bluecherry.net>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
1 file changed