Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/cachefiles/Kconfig b/fs/cachefiles/Kconfig
index 80e9c61..ae559ed 100644
--- a/fs/cachefiles/Kconfig
+++ b/fs/cachefiles/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 
 config CACHEFILES
 	tristate "Filesystem caching on files"