[media] v4l2-core: create MC interfaces for devnodes

V4L2 device (and subdevice) nodes should create an interface, if the
Media Controller support is enabled.

Please notice that radio devices should not create an entity, as radio
input/output is either via wires or via ALSA.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

include/media/v4l2-dev.h

@@ -86,6 +86,7 @@ struct video_device
 {
 #if defined(CONFIG_MEDIA_CONTROLLER)
 	struct media_entity entity;
+	struct media_intf_devnode *intf_devnode;
 #endif
 	/* device ops */
 	const struct v4l2_file_operations *fops;