[media] uvcvideo: Add iFunction or iInterface to device names

Permits distinguishing between two /dev/videoX entries from the same
physical UVC device (that naturally share the same iProduct name).

This change matches current Windows behavior by prioritizing iFunction
over iInterface, but unlike Windows it displays both iProduct and
iFunction/iInterface strings when both are available.

Signed-off-by: Peter Boström <pbos@google.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>