预充完成，增加两外两个电机的空挡

app/app_differential_drive.c

@@ -818,6 +818,8 @@ void preChargeFinish(void *signal_id)
 //    un_motor_output2.bit_data.gear = 0;
     publishMessage(&un_motor_output1, 1);
     publishMessage(&un_motor_output2, 1);
+    publishMessage(&un_motor_output3, 1);
+    publishMessage(&un_motor_output4, 1);    
 }