net: lapbether: fix double free

The function netdev_priv() returns the private data of the device. The
memory to store the private data is allocated in alloc_netdev() and is
released in netdev_free(). Calling kfree() on the return value of
netdev_priv() after netdev_free() results in a double free bug.
Signed-off-by: NPan Bian <bianpan2016@163.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/wan/lapbether.c

@@ -346,7 +346,6 @@ static int lapbeth_new_device(struct net_device *dev)
 fail:
 	dev_put(dev);
 	free_netdev(ndev);
-	kfree(lapbeth);
 	goto out;
 }