添加了不需要由 PWM 或 引脚 控制LCD背光时的背光控制空函数，防止编译报错
添加了不需要由 PWM 或 引脚 控制LCD背光时的背光控制空函数，防止编译报错

weiyuliang/rt-thread,weiyuliang/rt-thread,ArdaFu/rt-thread,RT-Thread/rt-thread,RT-Thread/rt-thread,hezlog/rt-thread,weety/rt-thread,geniusgogo/rt-thread,armink/rt-thread,weety/rt-thread,weiyuliang/rt-thread,geniusgogo/rt-thread,weety/rt-thread,armink/rt-thread,ArdaFu/rt-thread,weety/rt-thread,hezlog/rt-thread,hezlog/rt-thread,geniusgogo/rt-thread,ArdaFu/rt-thread,hezlog/rt-thread,weety/rt-thread,RT-Thread/rt-thread,geniusgogo/rt-thread,nongxiaoming/rt-thread,nongxiaoming/rt-thread,RT-Thread/rt-thread,nongxiaoming/rt-thread,RT-Thread/rt-thread,armink/rt-thread,weety/rt-thread,weiyuliang/rt-thread,ArdaFu/rt-thread,nongxiaoming/rt-thread,ArdaFu/rt-thread,armink/rt-thread,geniusgogo/rt-thread,geniusgogo/rt-thread,weety/rt-thread,hezlog/rt-thread,hezlog/rt-thread,armink/rt-thread,weiyuliang/rt-thread,nongxiaoming/rt-thread,RT-Thread/rt-thread,nongxiaoming/rt-thread,geniusgogo/rt-thread,armink/rt-thread,ArdaFu/rt-thread,weiyuliang/rt-thread,hezlog/rt-thread,RT-Thread/rt-thread,armink/rt-thread,ArdaFu/rt-thread,weiyuliang/rt-thread,nongxiaoming/rt-thread