Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/cpuidle/Kconfig.mips b/drivers/cpuidle/Kconfig.mips
index 512ee37..c3c011a 100644
--- a/drivers/cpuidle/Kconfig.mips
+++ b/drivers/cpuidle/Kconfig.mips
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 #
 # MIPS CPU Idle Drivers
 #