Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/xen/xen-acpi-pad.c b/drivers/xen/xen-acpi-pad.c
index 23d1808..ccd8012 100644
--- a/drivers/xen/xen-acpi-pad.c
+++ b/drivers/xen/xen-acpi-pad.c
@@ -1,17 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * xen-acpi-pad.c - Xen pad interface
  *
  * Copyright (c) 2012, Intel Corporation.
  *    Author: Liu, Jinsong <jinsong.liu@intel.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -19,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/acpi.h>
+#include <xen/xen.h>
 #include <xen/interface/version.h>
 #include <xen/xen-ops.h>
 #include <asm/xen/hypercall.h>