Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/media/conf_nitpick.py b/Documentation/media/conf_nitpick.py
index 480d548..d0c50d7 100644
--- a/Documentation/media/conf_nitpick.py
+++ b/Documentation/media/conf_nitpick.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8; mode: python -*-
 
+# SPDX-License-Identifier: GPL-2.0
+
 project = 'Linux Media Subsystem Documentation'
 
 # It is possible to run Sphinx in nickpick mode with: