message: fix USB buffer drop char error
diff: @@ -275,7 +275,7 @@ static int8_t CDC_Receive_FS (uint8_t* Buf, uint32_t *Len)
  int null_idx = MACRO_MIN(*Len, APP_RX_DATA_SIZE-1);
  Buf[null_idx] = 0;
  - motor_parse_cmd(Buf, *Len);
  + motor_parse_cmd(Buf, *Len+1);
  return (USBD_OK);
  /* USER CODE END 6 */
  