NFS: Add extra const qualifiers

Add some extra const qualifiers into NFS.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index dd9ae67..2426b11 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -833,9 +833,9 @@
 /*
  * Function vectors etc. for the NFS client
  */
-extern struct nfs_rpc_ops	nfs_v2_clientops;
-extern struct nfs_rpc_ops	nfs_v3_clientops;
-extern struct nfs_rpc_ops	nfs_v4_clientops;
+extern const struct nfs_rpc_ops	nfs_v2_clientops;
+extern const struct nfs_rpc_ops	nfs_v3_clientops;
+extern const struct nfs_rpc_ops	nfs_v4_clientops;
 extern struct rpc_version	nfs_version2;
 extern struct rpc_version	nfs_version3;
 extern struct rpc_version	nfs_version4;