Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/sound/pci/ctxfi/cttimer.c b/sound/pci/ctxfi/cttimer.c
index 2099e9c..0bb447c 100644
--- a/sound/pci/ctxfi/cttimer.c
+++ b/sound/pci/ctxfi/cttimer.c
@@ -1,9 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * PCM timer handling on ctxfi
- *
- * This source file is released under GPL v2 license (no other versions).
- * See the COPYING file included in the main directory of this source
- * distribution for the license terms and conditions.
  */
 
 #include <linux/slab.h>