net: toshiba: fix return type of ndo_start_xmit function

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type, so make sure the implementation in
this driver has returns 'netdev_tx_t' value, and change the function
return type to netdev_tx_t.

Found by coccinelle.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/toshiba/spider_net.c b/drivers/net/ethernet/toshiba/spider_net.c
index d925b82..2341726 100644
--- a/drivers/net/ethernet/toshiba/spider_net.c
+++ b/drivers/net/ethernet/toshiba/spider_net.c
@@ -880,9 +880,9 @@ spider_net_kick_tx_dma(struct spider_net_card *card)
  * @skb: packet to send out
  * @netdev: interface device structure
  *
- * returns 0 on success, !0 on failure
+ * returns NETDEV_TX_OK on success, NETDEV_TX_BUSY on failure
  */
-static int
+static netdev_tx_t
 spider_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	int cnt;