Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/6lowpan/nhc_fragment.c b/net/6lowpan/nhc_fragment.c
index 473dbc5..be85f07 100644
--- a/net/6lowpan/nhc_fragment.c
+++ b/net/6lowpan/nhc_fragment.c
@@ -1,10 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	6LoWPAN IPv6 Fragment Header compression according to RFC6282
- *
- *	This program is free software; you can redistribute it and/or
- *	modify it under the terms of the GNU General Public License
- *	as published by the Free Software Foundation; either version
- *	2 of the License, or (at your option) any later version.
  */
 
 #include "nhc.h"