arm: highbank: Add devicetree files

Add an empty version of this file, so that we can at least build this
board when devicetrees are required.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/highbank.dts b/arch/arm/dts/highbank.dts
new file mode 100644
index 0000000..1480bad
--- /dev/null
+++ b/arch/arm/dts/highbank.dts
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Empty devicetree for highbank/midway
+ */
+
+/dts-v1/;
+
+/ {
+};