media: v4l2-core: Add new metadata format

Add new metadata format to support metadata output in vivid.

Signed-off-by: Vandana BN <bnvandana@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>