mm/hugetlb.c: constify attribute_group structures

attribute_group are not supposed to change at runtime.  All functions
working with attribute_group provided by <linux/sysfs.h> work with const
attribute_group.  So mark the non-const structs as const.

Link: http://lkml.kernel.org/r/1501157260-3922-1-git-send-email-arvind.yadav.cs@gmail.com
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 1d54a13..cafd603 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2569,13 +2569,13 @@
 	NULL,
 };
 
-static struct attribute_group hstate_attr_group = {
+static const struct attribute_group hstate_attr_group = {
 	.attrs = hstate_attrs,
 };
 
 static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
 				    struct kobject **hstate_kobjs,
-				    struct attribute_group *hstate_attr_group)
+				    const struct attribute_group *hstate_attr_group)
 {
 	int retval;
 	int hi = hstate_index(h);
@@ -2633,7 +2633,7 @@
 	NULL,
 };
 
-static struct attribute_group per_node_hstate_attr_group = {
+static const struct attribute_group per_node_hstate_attr_group = {
 	.attrs = per_node_hstate_attrs,
 };