[media] media-entity.c: get rid of var length arrays

Fix those sparse warnings:
	drivers/media/media-entity.c:238:17: warning: Variable length array is used.
	drivers/media/media-entity.c:239:17: warning: Variable length array is used.

That allows sparse and other code check tools to verify if the
function is using more stack than allowed.

It also solves a bad Kernel pratice of using var length arrays
at the stack.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 153a464..767fe55 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -235,8 +235,8 @@
 	media_entity_graph_walk_start(&graph, entity);
 
 	while ((entity = media_entity_graph_walk_next(&graph))) {
-		DECLARE_BITMAP(active, entity->num_pads);
-		DECLARE_BITMAP(has_no_links, entity->num_pads);
+		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
+		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
 		unsigned int i;
 
 		entity->stream_count++;