math: Fix copyright header in erff.tst
This was incorrect in the previous commit.
diff --git a/math/test/testcases/directed/erff.tst b/math/test/testcases/directed/erff.tst
index 8d4ec40..d05b7b1 100644
--- a/math/test/testcases/directed/erff.tst
+++ b/math/test/testcases/directed/erff.tst
@@ -1,9 +1,7 @@
; erff.tst
;
-; Copyright 2009 ARM Limited. All rights reserved.
-;
-; $Id$
-; $URL$
+; Copyright (c) 2007-2020, Arm Limited.
+; SPDX-License-Identifier: MIT
func=erff op1=7fc00001 result=7fc00001 errno=0
func=erff op1=ffc00001 result=7fc00001 errno=0
