Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/um/drivers/Makefile b/arch/um/drivers/Makefile
index 6933198..a290821 100644
--- a/arch/um/drivers/Makefile
+++ b/arch/um/drivers/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 # 
 # Copyright (C) 2000, 2002, 2003 Jeff Dike (jdike@karaya.com)
-# Licensed under the GPL
 #
 
 # pcap is broken in 2.5 because kbuild doesn't allow pcap.a to be linked
@@ -61,6 +61,7 @@
 obj-$(CONFIG_UML_WATCHDOG) += harddog.o
 obj-$(CONFIG_BLK_DEV_COW_COMMON) += cow_user.o
 obj-$(CONFIG_UML_RANDOM) += random.o
+obj-$(CONFIG_VIRTIO_UML) += virtio_uml.o
 
 # pcap_user.o must be added explicitly.
 USER_OBJS := fd.o null.o pty.o tty.o xterm.o slip_common.o pcap_user.o vde_user.o vector_user.o