net: hns: Mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 114788 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -307,6 +307,7 @@ static int __lb_setup(struct net_device *ndev,
 		break;
 	case MAC_LOOP_PHY_NONE:
 		ret = hns_nic_config_phy_loopback(phy_dev, 0x0);
+		/* fall through */
 	case MAC_LOOP_NONE:
 		if (!ret && h->dev->ops->set_loopback) {
 			if (priv->ae_handle->phy_if != PHY_INTERFACE_MODE_XGMII)