netdev: convert bulk of drivers to netdev_tx_t

In a couple of cases collapse some extra code like:
   int retval = NETDEV_TX_OK;
   ...
   return retval;
into
   return NETDEV_TX_OK;

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tehuti.c b/drivers/net/tehuti.c
index 3c2679c..918d4c9 100644
--- a/drivers/net/tehuti.c
+++ b/drivers/net/tehuti.c
@@ -1622,7 +1622,8 @@
  *   the driver. Note: the driver must NOT put the skb in its DMA ring.
  * o NETDEV_TX_LOCKED Locking failed, please retry quickly.
  */
-static int bdx_tx_transmit(struct sk_buff *skb, struct net_device *ndev)
+static netdev_tx_t bdx_tx_transmit(struct sk_buff *skb,
+				   struct net_device *ndev)
 {
 	struct bdx_priv *priv = netdev_priv(ndev);
 	struct txd_fifo *f = &priv->txd_fifo0;