Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/squashfs/decompressor_multi.c b/fs/squashfs/decompressor_multi.c
index d6008a6..c181dee 100644
--- a/fs/squashfs/decompressor_multi.c
+++ b/fs/squashfs/decompressor_multi.c
@@ -1,9 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  *  Copyright (c) 2013
  *  Minchan Kim <minchan@kernel.org>
- *
- *  This work is licensed under the terms of the GNU GPL, version 2. See
- *  the COPYING file in the top-level directory.
  */
 #include <linux/types.h>
 #include <linux/mutex.h>