As we'll be adding other interface types in the future, put the
common interface create code on a separate function.
Suggested-by: NHans Verkuil <hans.verkuil@cisco.com>
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>