Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/dma/zx_dma.c b/drivers/dma/zx_dma.c
index 2571bc7..9f4436f 100644
--- a/drivers/dma/zx_dma.c
+++ b/drivers/dma/zx_dma.c
@@ -1,9 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright 2015 Linaro.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 #include <linux/sched.h>
 #include <linux/device.h>