net/netdev: fix switch case missing break

Signed-off-by: chao.an <anchao@xiaomi.com>

net/netdev/netdev_ioctl.c

@@ -1530,6 +1530,7 @@ static int netdev_file_ioctl(FAR struct socket *psock, int cmd,
               ret = -ENOSYS;
             }
         }
+        break;
 
       default:
         ret = -ENOTTY;