servod: add power_tools.xml by default

Right now measure_power breaks if no power map (i.e. poppy_r3.xml) is
not added to servod. It breaks because the introspection controls are
not available. This adds the power introspection to all servod
invocations.

BUG=chromium:806146
TEST=manual testing
sudo servod -b soraka
dut-control raw_calib_rails
> raw_calib_rails:

Change-Id: If33dac1c8c970bde0b94beea6fd8992bc366910e
Reviewed-on: https://chromium-review.googlesource.com/1195271
Commit-Ready: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Tested-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Reviewed-by: Todd Broch <tbroch@chromium.org>
diff --git a/servo/data/common.xml b/servo/data/common.xml
index 53d216d..50cf024 100644
--- a/servo/data/common.xml
+++ b/servo/data/common.xml
@@ -1,5 +1,8 @@
 <?xml version="1.0"?>
 <root>
+  <include>
+    <name>power_tools.xml</name>
+  </include>
   <map>
     <name>onoff</name>
     <doc>assertive high map for on/off</doc>