Merge pull request #139 from heyuanjie87/master

修正esp32在64位下出现的非对齐异常

class/esp32/at_device_esp32.c

@@ -56,7 +56,7 @@ static void esp32_get_netdev_info(struct rt_work *work, void *work_data)
     ip_addr_t ip_addr;
     rt_uint32_t mac_addr[6] = {0};
     rt_uint32_t num = 0;
-    rt_uint8_t dhcp_stat = 0;
+    rt_uint32_t dhcp_stat = 0;
     struct rt_delayed_work *delay_work = (struct rt_delayed_work *)work;
     struct at_device *device = (struct at_device *)work_data;
     struct netdev *netdev = device->netdev;