ymodem_ota 升级时卡住问题

现象：插着网线升级时，升级进度很容易卡住解决方法：[文章1](https://club.rt-thread.org/ask/article/9b7f5db2994a76cb.html "文章1") [文章2](https://github.com/RT-Thread/rt-thread/pull/