Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/sh/boards/mach-cayman/panic.c b/arch/sh/boards/mach-cayman/panic.c
index d1e6730..cfc4631 100644
--- a/arch/sh/boards/mach-cayman/panic.c
+++ b/arch/sh/boards/mach-cayman/panic.c
@@ -1,9 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2003  Richard Curnow, SuperH UK Limited
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
  */
 
 #include <linux/kernel.h>