mm/hugetlb: make node_hstates array static

There are no users of the node_hstates array outside of the
mm/hugetlb.c. So let's make it static.
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -2376,7 +2376,7 @@ struct node_hstate {
 	struct kobject		*hugepages_kobj;
 	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
 };
-struct node_hstate node_hstates[MAX_NUMNODES];
+static struct node_hstate node_hstates[MAX_NUMNODES];
 
 /*
  * A subset of global hstate attributes for node devices