Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/sh/maple/Makefile b/drivers/sh/maple/Makefile
index 65dfeeb..c3a8091 100644
--- a/drivers/sh/maple/Makefile
+++ b/drivers/sh/maple/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 # Makefile for Maple Bus
 
 obj-$(CONFIG_MAPLE) := maple.o