clearfog: prepare DTS for the testing board

There's value in not dying too early when manually prototyping boards,
etc.

Change-Id: Ife66911b290ed9978cd3bd820694d6f0e1c86dbb
diff --git a/board/czechlight/clearfog/sdn-roadm-testing-clearfog.dts b/board/czechlight/clearfog/sdn-roadm-testing-clearfog.dts
new file mode 100644
index 0000000..39f5e7a
--- /dev/null
+++ b/board/czechlight/clearfog/sdn-roadm-testing-clearfog.dts
@@ -0,0 +1 @@
+#include "sdn-roadm-clearfog.dtsi"