media: mc: entity: Fix doc for media_graph_walk_init

There is no media_graph_walk_free(). media_graph_walk_cleanup() is used
to release the resources.
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/mc/mc-entity.c

@@ -308,7 +308,7 @@ static struct media_entity *stack_pop(struct media_graph *graph)
  *
  * Reserve resources for graph walk in media device's current
  * state. The memory must be released using
- * media_graph_walk_free().
+ * media_graph_walk_cleanup().
  *
  * Returns error on failure, zero on success.
  */