net: ni: Fix use correct return type for ndo_start_xmit()

The method ndo_start_xmit() returns a value of type netdev_tx_t. Fix
the ndo function to use the correct type.
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ni/nixge.c

@@ -502,7 +502,8 @@ static int nixge_check_tx_bd_space(struct nixge_priv *priv,
 	return 0;
 }
 
-static int nixge_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+static netdev_tx_t nixge_start_xmit(struct sk_buff *skb,
+				    struct net_device *ndev)
 {
 	struct nixge_priv *priv = netdev_priv(ndev);
 	struct nixge_hw_dma_bd *cur_p;