Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/lib/clz_ctz.c b/lib/clz_ctz.c
index 2e11e48..0d3a686 100644
--- a/lib/clz_ctz.c
+++ b/lib/clz_ctz.c
@@ -1,11 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * lib/clz_ctz.c
  *
  * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  * The functions in this file aren't called directly, but are required by
  * GCC builtins such as __builtin_ctz, and therefore they can't be removed
  * despite appearing unreferenced in kernel source.