Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/c6x/kernel/switch_to.S b/arch/c6x/kernel/switch_to.S
index 09177ed..b7f9f60 100644
--- a/arch/c6x/kernel/switch_to.S
+++ b/arch/c6x/kernel/switch_to.S
@@ -1,10 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  *  Copyright (C) 2011 Texas Instruments Incorporated
  *  Author: Mark Salter (msalter@redhat.com)
- *
- *  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.
  */
 
 #include <linux/linkage.h>