[media] media: Move media_device link_notify operation to an ops structure

This will allow adding new operations without increasing the
media_device structure size for drivers that don't implement any media
device operation.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

include/media/media-device.h

@@ -48,6 +48,16 @@ struct media_entity_notify {
 	void (*notify)(struct media_entity *entity, void *notify_data);
 };
 
+/**
+ * struct media_device_ops - Media device operations
+ * @link_notify: Link state change notification callback. This callback is
+ *		 called with the graph_mutex held.
+ */
+struct media_device_ops {
+	int (*link_notify)(struct media_link *link, u32 flags,
+			   unsigned int notification);
+};
+
 /**
  * struct media_device - Media device
  * @dev:	Parent device
@@ -80,8 +90,7 @@ struct media_entity_notify {
  * @enable_source: Enable Source Handler function pointer
  * @disable_source: Disable Source Handler function pointer
  *
- * @link_notify: Link state change notification callback. This callback is
- *		 called with the graph_mutex held.
+ * @ops:	Operation handler callbacks
  *
  * This structure represents an abstract high-level media device. It allows easy
  * access to entities and provides basic media device-level support. The
@@ -150,8 +159,7 @@ struct media_device {
 			     struct media_pipeline *pipe);
 	void (*disable_source)(struct media_entity *entity);
 
-	int (*link_notify)(struct media_link *link, u32 flags,
-			   unsigned int notification);
+	const struct media_device_ops *ops;
 };
 
 /* We don't need to include pci.h or usb.h here */