elm: Add the servo overlay

Inherit Oak configuration.

BUG=chrome-os-partner:51303
TEST=sudo servod -b elm

Change-Id: I3a297dc86461967d909b89326d539404463be5e2
Signed-off-by: Yidi Lin <yidi.lin@mediatek.com>
Reviewed-on: https://chromium-review.googlesource.com/333850
Commit-Ready: Paris Yeh <pyeh@chromium.org>
Reviewed-by: Paris Yeh <pyeh@chromium.org>
diff --git a/servo/data/servo_elm_overlay.xml b/servo/data/servo_elm_overlay.xml
new file mode 100644
index 0000000..8357f72
--- /dev/null
+++ b/servo/data/servo_elm_overlay.xml
@@ -0,0 +1,5 @@
+<root>
+  <include>
+    <name>servo_oak_overlay.xml</name>
+  </include>
+</root>