SUNRPC: nfsacl_encode/nfsacl_decode should be exported as GPL-only

Again, this has never been intended as a public abi for out-of-tree
modules.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs_common/nfsacl.c

@@ -29,8 +29,8 @@
 
 MODULE_LICENSE("GPL");
 
-EXPORT_SYMBOL(nfsacl_encode);
-EXPORT_SYMBOL(nfsacl_decode);
+EXPORT_SYMBOL_GPL(nfsacl_encode);
+EXPORT_SYMBOL_GPL(nfsacl_decode);
 
 struct nfsacl_encode_desc {
 	struct xdr_array2_desc desc;