net: renesas: 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: NYunjian Wang <wangyunjian@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -2472,7 +2472,8 @@ static void sh_eth_tx_timeout(struct net_device *ndev, unsigned int txqueue)
 }
 
 /* Packet transmit function */
-static int sh_eth_start_xmit(struct sk_buff *skb, struct net_device *ndev)
+static netdev_tx_t sh_eth_start_xmit(struct sk_buff *skb,
+				     struct net_device *ndev)
 {
 	struct sh_eth_private *mdp = netdev_priv(ndev);
 	struct sh_eth_txdesc *txdesc;