Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/nds32/lib/Makefile b/arch/nds32/lib/Makefile
index 0f98401..dddbc15 100644
--- a/arch/nds32/lib/Makefile
+++ b/arch/nds32/lib/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 lib-y		:= copy_page.o memcpy.o memmove.o   \
 		   memset.o memzero.o \
 		   copy_from_user.o copy_to_user.o clear_user.o