Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/sched/sch_plug.c b/net/sched/sch_plug.c
index 5619d2e..cbc2ebc 100644
--- a/net/sched/sch_plug.c
+++ b/net/sched/sch_plug.c
@@ -1,11 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * sch_plug.c Queue traffic until an explicit release command
  *
- *             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.
- *
  * There are two ways to use this qdisc:
  * 1. A simple "instantaneous" plug/unplug operation, by issuing an alternating
  *    sequence of TCQ_PLUG_BUFFER & TCQ_PLUG_RELEASE_INDEFINITE commands.