quota: constify qtree_fmt_operations structures

The qtree_fmt_operations structures are never modified, so declare them as
const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index c93d6722..fde9ef1 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -123,7 +123,7 @@
 		      dquot->dq_id);
 }
 
-struct qtree_fmt_operations ocfs2_global_ops = {
+const struct qtree_fmt_operations ocfs2_global_ops = {
 	.mem2disk_dqblk = ocfs2_global_mem2diskdqb,
 	.disk2mem_dqblk = ocfs2_global_disk2memdqb,
 	.is_id = ocfs2_global_is_id,