[media] v4l: vsp1: Replace container_of() with dedicated macro

Add a macro to cast from a struct media_entity to a struct vsp1_entity
to replace the manual implementations.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/vsp1/vsp1_entity.c

@@ -22,6 +22,12 @@
 #include "vsp1_dl.h"
 #include "vsp1_entity.h"
 
+static inline struct vsp1_entity *
+media_entity_to_vsp1_entity(struct media_entity *entity)
+{
+	return container_of(entity, struct vsp1_entity, subdev.entity);
+}
+
 void vsp1_entity_route_setup(struct vsp1_entity *source,
 			     struct vsp1_dl_list *dl)
 {
@@ -30,7 +36,7 @@ void vsp1_entity_route_setup(struct vsp1_entity *source,
 	if (source->route->reg == 0)
 		return;
 
-	sink = container_of(source->sink, struct vsp1_entity, subdev.entity);
+	sink = media_entity_to_vsp1_entity(source->sink);
 	vsp1_dl_list_write(dl, source->route->reg,
 			   sink->route->inputs[source->sink_pad]);
 }
@@ -252,7 +258,7 @@ int vsp1_entity_link_setup(struct media_entity *entity,
 	if (!(local->flags & MEDIA_PAD_FL_SOURCE))
 		return 0;
 
-	source = container_of(local->entity, struct vsp1_entity, subdev.entity);
+	source = media_entity_to_vsp1_entity(local->entity);
 
 	if (!source->route)
 		return 0;