Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/sound/mips/Kconfig b/sound/mips/Kconfig
index 4a47050..8a33402 100644
--- a/sound/mips/Kconfig
+++ b/sound/mips/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 # ALSA MIPS drivers
 
 menuconfig SND_MIPS