Ultima: Add servo overlay for ultima

Inherit Strago servo overlay configuration.

BUG=chrome-os-partner:43821
TEST=run 'cros_workon --host start hdctools'
         'sudo emerge hdctools'
         'sudo servod --board=ultima'

Change-Id: I75427aefa1d48ab204f479bd3785a92f667f891e
Reviewed-on: https://chromium-review.googlesource.com/293165
Tested-by: Keith Tzeng <keith.tzeng@quantatw.com>
Reviewed-by: Shawn N <shawnn@chromium.org>
Commit-Queue: Keith Tzeng <keith.tzeng@quantatw.com>
diff --git a/servo/data/servo_ultima_overlay.xml b/servo/data/servo_ultima_overlay.xml
new file mode 100644
index 0000000..dcdb8e8
--- /dev/null
+++ b/servo/data/servo_ultima_overlay.xml
@@ -0,0 +1,5 @@
+<root>
+  <include>
+    <name>servo_strago_overlay.xml</name>
+  </include>
+</root>