Plane: don't do accel calibration in HIL mode

this should fix the hang on startup

ArduPlane/system.pde

@@ -435,12 +435,14 @@ static void startup_INS_ground(bool force_accel_level)
     mavlink_delay(1000);
 
     ins.init(AP_InertialSensor::COLD_START, mavlink_delay, flash_leds, &timer_scheduler);
+#if HIL_MODE == HIL_MODE_DISABLED
     if (force_accel_level || g.manual_level == 0) {
         // when MANUAL_LEVEL is set to 1 we don't do accelerometer
         // levelling on each boot, and instead rely on the user to do
         // it once via the ground station
         ins.init_accel(mavlink_delay, flash_leds);
     }
+#endif
     ahrs.set_fly_forward(true);
     ahrs.reset();