Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/powerpc/sysdev/xive/Makefile b/arch/powerpc/sysdev/xive/Makefile
index 536d6e5..e510888 100644
--- a/arch/powerpc/sysdev/xive/Makefile
+++ b/arch/powerpc/sysdev/xive/Makefile
@@ -1,4 +1,4 @@
-subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
+# SPDX-License-Identifier: GPL-2.0-only
 
 obj-y				+= common.o
 obj-$(CONFIG_PPC_XIVE_NATIVE)	+= native.o