scripts/dtc: Update to upstream version v1.4.3

Using the update-dtc-source.sh script from Linux v4.14-rc1 import the
portions of dtc that we require.  We bring in update-dtc-source.sh and
scripts/dtc/Makefile from Linux v4.14-rc1.  Rework DTC_FLAGS handling to
not require a test.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/scripts/dtc/libfdt/Makefile.libfdt b/scripts/dtc/libfdt/Makefile.libfdt
new file mode 100644
index 0000000..098b3f3
--- /dev/null
+++ b/scripts/dtc/libfdt/Makefile.libfdt
@@ -0,0 +1,11 @@
+# Makefile.libfdt
+#
+# This is not a complete Makefile of itself.  Instead, it is designed to
+# be easily embeddable into other systems of Makefiles.
+#
+LIBFDT_soname = libfdt.$(SHAREDLIB_EXT).1
+LIBFDT_INCLUDES = fdt.h libfdt.h libfdt_env.h
+LIBFDT_VERSION = version.lds
+LIBFDT_SRCS = fdt.c fdt_ro.c fdt_wip.c fdt_sw.c fdt_rw.c fdt_strerror.c fdt_empty_tree.c \
+	fdt_addresses.c fdt_overlay.c
+LIBFDT_OBJS = $(LIBFDT_SRCS:%.c=%.o)