Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/samples/bpf/tracex3_user.c b/samples/bpf/tracex3_user.c
index 6c6b10f..cf8fedc 100644
--- a/samples/bpf/tracex3_user.c
+++ b/samples/bpf/tracex3_user.c
@@ -1,8 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of version 2 of the GNU General Public
- * License as published by the Free Software Foundation.
  */
 #include <stdio.h>
 #include <stdlib.h>
@@ -17,8 +14,6 @@
 #include "bpf_load.h"
 #include "bpf_util.h"
 
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
-
 #define SLOTS 100
 
 static void clear_stats(int fd)