Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/mips/generic/irq.c b/arch/mips/generic/irq.c
index cb7fdae..9331192 100644
--- a/arch/mips/generic/irq.c
+++ b/arch/mips/generic/irq.c
@@ -1,11 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2016 Imagination Technologies
  * Author: Paul Burton <paul.burton@mips.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.
  */
 
 #include <linux/clk.h>