Rover: fixed typo in log write

APMrover2/cruise_learn.cpp

@@ -64,7 +64,7 @@ void Rover::cruise_learn_complete()
 void Rover::log_write_cruise_learn()
 {
     AP::logger().Write("CRSE", "TimeUS,State,Speed,Throttle", "Qbff",
-                                            AP_HAL::micros64,
+                       AP_HAL::micros64(),
                        cruise_learn.learn_start_ms > 0,
                        cruise_learn.speed_filt.get(),
                        cruise_learn.throttle_filt.get());