AP_AHRS: fix example sketch

libraries/AP_AHRS/examples/AHRS_Test/AHRS_Test.cpp

@@ -21,7 +21,7 @@ AP_SerialManager serial_manager;
 
 class DummyVehicle {
 public:
-    RangeFinder sonar {serial_manager};
+    RangeFinder sonar {serial_manager, ROTATION_PITCH_270};
     AP_AHRS_NavEKF ahrs{ins, barometer, gps, sonar, EKF2, EKF3,
                         AP_AHRS_NavEKF::FLAG_ALWAYS_USE_EKF};
     NavEKF2 EKF2{&ahrs, barometer, sonar};