Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/arm/mm/cache-nop.S b/arch/arm/mm/cache-nop.S
index f1cc986..72d939e 100644
--- a/arch/arm/mm/cache-nop.S
+++ b/arch/arm/mm/cache-nop.S
@@ -1,8 +1,4 @@
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
+/* SPDX-License-Identifier: GPL-2.0-only */
 #include <linux/linkage.h>
 #include <linux/init.h>
 #include <asm/assembler.h>