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.h b/fs/ocfs2/quota.h
index b6d5133..d153e6e 100644
--- a/fs/ocfs2/quota.h
+++ b/fs/ocfs2/quota.h
@@ -82,7 +82,7 @@
 extern struct kmem_cache *ocfs2_dquot_cachep;
 extern struct kmem_cache *ocfs2_qf_chunk_cachep;
 
-extern struct qtree_fmt_operations ocfs2_global_ops;
+extern const struct qtree_fmt_operations ocfs2_global_ops;
 
 struct ocfs2_quota_recovery *ocfs2_begin_quota_recovery(
 				struct ocfs2_super *osb, int slot_num);