修复因串口接收缓冲区满且没有开启ULOG_USING_ISR_LOG而造成的死机问题

components/drivers/serial/serial.c

@@ -333,8 +333,10 @@ static void _serial_check_buffer_size(void)
 
     if (already_output == RT_FALSE)
     {
+#if defined(ULOG_USING_ISR_LOG)
         LOG_W("Warning: There is no enough buffer for saving data,"
               " please increase the RT_SERIAL_RB_BUFSZ option.");
+#endif
         already_output = RT_TRUE;
     }
 }
@@ -1286,4 +1288,3 @@ void rt_hw_serial_isr(struct rt_serial_device *serial, int event)
 #endif /* RT_SERIAL_USING_DMA */
     }
 }
-