IB/ipoib: fix ipoib_start_xmit()'s return type

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type, but the implementation in this
driver returns an 'int'.

Fix this by returning 'netdev_tx_t' in this driver too.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/ipoib/ipoib_main.c

@@ -1094,7 +1094,7 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
 	spin_unlock_irqrestore(&priv->lock, flags);
 }
 
-static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = ipoib_priv(dev);
 	struct rdma_netdev *rn = netdev_priv(dev);