Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
index 0a86f1e..6a1d354 100644
--- a/drivers/net/phy/mdio-mux.c
+++ b/drivers/net/phy/mdio-mux.c
@@ -1,8 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
  * Copyright (C) 2011, 2012 Cavium, Inc.
  */
 
@@ -210,4 +207,4 @@
 
 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 MODULE_AUTHOR("David Daney");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");