[media] media-entity: must check media_create_pad_link()

Drivers should check if media_create_pad_link() actually
worked.

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

include/media/media-entity.h

@@ -351,8 +351,9 @@ int media_entity_init(struct media_entity *entity, u16 num_pads,
 		      struct media_pad *pads);
 void media_entity_cleanup(struct media_entity *entity);
 
-int media_create_pad_link(struct media_entity *source, u16 source_pad,
-		struct media_entity *sink, u16 sink_pad, u32 flags);
+__must_check int media_create_pad_link(struct media_entity *source,
+			u16 source_pad, struct media_entity *sink,
+			u16 sink_pad, u32 flags);
 void __media_entity_remove_links(struct media_entity *entity);
 void media_entity_remove_links(struct media_entity *entity);