Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/csky/mm/Makefile b/arch/csky/mm/Makefile
new file mode 100644
index 0000000..c94ef64
--- /dev/null
+++ b/arch/csky/mm/Makefile
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+ifeq ($(CONFIG_CPU_HAS_CACHEV2),y)
+obj-y +=			cachev2.o
+else
+obj-y +=			cachev1.o
+endif
+
+obj-y +=			dma-mapping.o
+obj-y +=			fault.o
+obj-$(CONFIG_HIGHMEM) +=	highmem.o
+obj-y +=			init.o
+obj-y +=			ioremap.o
+obj-y +=			syscache.o
+obj-y +=			tlb.o
+obj-y +=			asid.o
+obj-y +=			context.o