Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
index be0d4a5..0cf2748 100644
--- a/samples/kfifo/dma-example.c
+++ b/samples/kfifo/dma-example.c
@@ -1,10 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Sample fifo dma implementation
  *
  * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
- *
- * Released under the GPL version 2 only.
- *
  */
 
 #include <linux/init.h>