Update ry_sy.c
Update ry_sy.c

修改了读取不到文件大小，导致的文件传输的问题，问题说明在
https://www.rt-thread.org/qa/forum.php?mod=viewthread&tid=423781
weety/rt-thread,geniusgogo/rt-thread,RT-Thread/rt-thread,weiyuliang/rt-thread,RT-Thread/rt-thread,weiyuliang/rt-thread,weety/rt-thread,weety/rt-thread,armink/rt-thread,armink/rt-thread,geniusgogo/rt-thread,weiyuliang/rt-thread,ArdaFu/rt-thread,weiyuliang/rt-thread,nongxiaoming/rt-thread,RT-Thread/rt-thread,armink/rt-thread,armink/rt-thread,geniusgogo/rt-thread,ArdaFu/rt-thread,weiyuliang/rt-thread,geniusgogo/rt-thread,nongxiaoming/rt-thread,geniusgogo/rt-thread,armink/rt-thread,nongxiaoming/rt-thread,hezlog/rt-thread,nongxiaoming/rt-thread,RT-Thread/rt-thread,hezlog/rt-thread,weety/rt-thread,ArdaFu/rt-thread,armink/rt-thread,RT-Thread/rt-thread,ArdaFu/rt-thread,weiyuliang/rt-thread,nongxiaoming/rt-thread,weety/rt-thread,hezlog/rt-thread,nongxiaoming/rt-thread,ArdaFu/rt-thread,armink/rt-thread,ArdaFu/rt-thread,geniusgogo/rt-thread,hezlog/rt-thread,hezlog/rt-thread,nongxiaoming/rt-thread,hezlog/rt-thread,weety/rt-thread,RT-Thread/rt-thread,ArdaFu/rt-thread,weiyuliang/rt-thread,hezlog/rt-thread,geniusgogo/rt-thread,weety/rt-thread,RT-Thread/rt-thread