Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/sys_soc.h b/include/linux/sys_soc.h
index bed223b..48ceea8 100644
--- a/include/linux/sys_soc.h
+++ b/include/linux/sys_soc.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (C) ST-Ericsson SA 2011
  * Author: Lee Jones <lee.jones@linaro.org> for ST-Ericsson.
- * License terms:  GNU General Public License (GPL), version 2
  */
 #ifndef __SOC_BUS_H
 #define __SOC_BUS_H
@@ -12,6 +12,7 @@
 	const char *machine;
 	const char *family;
 	const char *revision;
+	const char *serial_number;
 	const char *soc_id;
 	const void *data;
 };