Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/media/dvb-drivers/intro.rst b/Documentation/media/dvb-drivers/intro.rst
index d6eeb27..4e361bc 100644
--- a/Documentation/media/dvb-drivers/intro.rst
+++ b/Documentation/media/dvb-drivers/intro.rst
@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: GPL-2.0
+
 Introduction
 ============