Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/arm/mach-keystone/keystone.c b/arch/arm/mach-keystone/keystone.c
index 84613ab..638808c 100644
--- a/arch/arm/mach-keystone/keystone.c
+++ b/arch/arm/mach-keystone/keystone.c
@@ -1,13 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Keystone2 based boards and SOC related code.
  *
  * Copyright 2013 Texas Instruments, Inc.
  *	Cyril Chemparathy <cyril@ti.com>
  *	Santosh Shilimkar <santosh.shillimkar@ti.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
  */
 #include <linux/io.h>
 #include <linux/of.h>