TradHeli: Set main loop rate time in motors class.

ArduCopter/heli.pde

@@ -17,6 +17,7 @@ static int8_t heli_dynamic_flight_counter;
 static void heli_init()
 {
     attitude_control.update_feedforward_filter_rates(MAIN_LOOP_SECONDS);
+    motors.set_dt(MAIN_LOOP_SECONDS);
 }
 
 // get_pilot_desired_collective - converts pilot input (from 0 ~ 1000) to a value that can be fed into the g.rc_3.servo_out function