net: hns: add netif_carrier_off before change speed and duplex

If there are packets in hardware when changing the speed
or duplex, it may cause hardware hang up.

This patch adds netif_carrier_off before change speed and
duplex in ethtool_ops.set_link_ksettings, and adds
netif_carrier_on after complete the change.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns/hns_ethtool.c

@@ -243,7 +243,9 @@ static int hns_nic_set_link_ksettings(struct net_device *net_dev,
 	}
 
 	if (h->dev->ops->adjust_link) {
+		netif_carrier_off(net_dev);
 		h->dev->ops->adjust_link(h, (int)speed, cmd->base.duplex);
+		netif_carrier_on(net_dev);
 		return 0;
 	}