fix(serial,drv_pin): 修复serial方法检查错误，修复PIN驱动中断关闭错误

感谢Lucas反馈问题

device/serial.c

@@ -276,7 +276,7 @@ static int mr_serial_ioctl(struct mr_dev *dev, int cmd, void *args)
             if (args != MR_NULL) {
                 size_t bufsz = *(size_t *)args;
 
-                if (ops->stop_dma_rx) {
+                if (ops->stop_dma_rx == MR_NULL) {
                     return MR_EIO;
                 }
                 ops->stop_dma_rx(serial);
@@ -299,6 +299,10 @@ static int mr_serial_ioctl(struct mr_dev *dev, int cmd, void *args)
             if (args != MR_NULL) {
                 size_t bufsz = *(size_t *)args;
 
+                if (serial->nonblock_state != MR_DISABLE) {
+                    return MR_EBUSY;
+                }
+
                 uint8_t *pool = mr_realloc(serial->dma_wr_buf, bufsz);
                 if ((pool == MR_NULL) && (bufsz != 0)) {
                     return MR_ENOMEM;