HAL_PX4: disable "Overtime in task" msg

this hasn't helped us find any bugs and it is very annoying with nsh
over MAVLink

libraries/AP_HAL_PX4/Scheduler.cpp

@@ -280,8 +280,10 @@ void *PX4Scheduler::_timer_thread(void *arg)
 
         if (px4_ran_overtime && AP_HAL::millis() - last_ran_overtime > 2000) {
             last_ran_overtime = AP_HAL::millis();
+#if 0
             printf("Overtime in task %d\n", (int)AP_Scheduler::current_task);
             hal.console->printf("Overtime in task %d\n", (int)AP_Scheduler::current_task);
+#endif
         }
     }
     return NULL;