[media] media-entity: enforce check of interface and links creation

Drivers should check if interfaces and interface links were
created. Add a must_check for them.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

include/media/media-entity.h

@@ -373,12 +373,14 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
 					     struct media_pipeline *pipe);
 void media_entity_pipeline_stop(struct media_entity *entity);
 
-struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
+struct media_intf_devnode *
+__must_check media_devnode_create(struct media_device *mdev,
 				  u32 type, u32 flags,
 				  u32 major, u32 minor,
 				  gfp_t gfp_flags);
 void media_devnode_remove(struct media_intf_devnode *devnode);
-struct media_link *media_create_intf_link(struct media_entity *entity,
+struct media_link *
+__must_check media_create_intf_link(struct media_entity *entity,
 				    struct media_interface *intf,
 				    u32 flags);
 void __media_remove_intf_link(struct media_link *link);