media: mc: Add nop implementations of media_device_{init,cleanup}

To support compilation with Media controller disabled, drivers were
required to conditionally call media_device_init and media_device_cleanup.
Add nop implementations of both so drivers don't need to care (or at least
care less).

Signed-off-by: Sakari Ailus <[e-mail]>
Acked-by: Hans Verkuil <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

include/media/media-device.h

···
 			     const char *driver_name);
 
 #else
+static inline void media_device_init(struct media_device *mdev)
+{
+}
 static inline int media_device_register(struct media_device *mdev)
 {
 	return 0;
 }
 static inline void media_device_unregister(struct media_device *mdev)
+{
+}
+static inline void media_device_cleanup(struct media_device *mdev)
 {
 }
 static inline int media_device_register_entity(struct media_device *mdev,