Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/hdlc.h b/include/linux/hdlc.h
index 97585d9..cacc4dd 100644
--- a/include/linux/hdlc.h
+++ b/include/linux/hdlc.h
@@ -1,11 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Generic HDLC support routines for Linux
  *
  * Copyright (C) 1999-2005 Krzysztof Halasa <khc@pm.waw.pl>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of version 2 of the GNU General Public License
- * as published by the Free Software Foundation.
  */
 #ifndef __HDLC_H
 #define __HDLC_H