Made pistol grip controller work with the drivetrain.

Change-Id: Id5ede34e9a9981c338aaa6118eb5085578a8ecd3
diff --git a/y2012/joystick_reader.cc b/y2012/joystick_reader.cc
index 24c1b6c..3b5bc48 100644
--- a/y2012/joystick_reader.cc
+++ b/y2012/joystick_reader.cc
@@ -100,7 +100,7 @@
       is_high_gear_ = true;
     }
     if (!drivetrain_queue.goal.MakeWithBuilder()
-             .steering(wheel)
+             .wheel(wheel)
              .throttle(throttle)
              .highgear(is_high_gear_)
              .quickturn(data.IsPressed(kQuickTurn))