Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/powerpc/kernel/io.c b/arch/powerpc/kernel/io.c
index 2a2b4ae..2f29b7d 100644
--- a/arch/powerpc/kernel/io.c
+++ b/arch/powerpc/kernel/io.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * I/O string operations
  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
@@ -10,11 +11,6 @@
  * PPC64 updates by Dave Engebretsen (engebret@us.ibm.com)
  *
  * Rewritten in C by Stephen Rothwell.
- *
- * 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.
  */
 #include <linux/kernel.h>
 #include <linux/types.h>