Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/perf/util/setns.c b/tools/perf/util/setns.c
index ce8fc29..48f9c0a 100644
--- a/tools/perf/util/setns.c
+++ b/tools/perf/util/setns.c
@@ -1,4 +1,6 @@
-#include "util.h"
+// SPDX-License-Identifier: LGPL-2.1
+
+#include "namespaces.h"
 #include <unistd.h>
 #include <sys/syscall.h>