Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/lib/atomic64_test.c b/lib/atomic64_test.c
index 62ab629..d9d1702 100644
--- a/lib/atomic64_test.c
+++ b/lib/atomic64_test.c
@@ -1,12 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Testsuite for atomic64_t functions
  *
  * Copyright © 2010  Luca Barbieri
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt