Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/iio/buffer/industrialio-buffer-dma.c b/drivers/iio/buffer/industrialio-buffer-dma.c
index b32bf57..90cf6e5 100644
--- a/drivers/iio/buffer/industrialio-buffer-dma.c
+++ b/drivers/iio/buffer/industrialio-buffer-dma.c
@@ -1,8 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright 2013-2015 Analog Devices Inc.
  *  Author: Lars-Peter Clausen <lars@metafoo.de>
- *
- * Licensed under the GPL-2.
  */
 
 #include <linux/slab.h>