Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/sound/Kconfig b/sound/Kconfig
index 1140e99..3678541 100644
--- a/sound/Kconfig
+++ b/sound/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 menuconfig SOUND
 	tristate "Sound card support"
 	depends on HAS_IOMEM