Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/include/linux/log2.h b/tools/include/linux/log2.h
index 0325cef..e20a67d 100644
--- a/tools/include/linux/log2.h
+++ b/tools/include/linux/log2.h
@@ -1,12 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /* Integer base 2 logarithm calculation
  *
  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
- *
- * 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.
  */
 
 #ifndef _TOOLS_LINUX_LOG2_H