net: mhi: Fix memory leak in mhi_net_dellink()

MHI driver registers network device without setting the
needs_free_netdev flag, and does NOT call free_netdev() when
unregisters network device, which causes a memory leak.

This patch calls free_netdev() to fix it since netdev_priv
is used after unregister.

Fixes: 13adac03 ("net: mhi_net: Register wwan_ops for link creation")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/mhi_net.c

@@ -343,6 +343,8 @@ static void mhi_net_dellink(struct mhi_device *mhi_dev, struct net_device *ndev)
 
 	kfree_skb(mhi_netdev->skbagg_head);
 
+	free_netdev(ndev);
+
 	dev_set_drvdata(&mhi_dev->dev, NULL);
 }