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>

drivers/net/depca.c

@@ -516,7 +516,8 @@ struct depca_private {
 ** Public Functions
 */
 static int depca_open(struct net_device *dev);
-static int depca_start_xmit(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t depca_start_xmit(struct sk_buff *skb,
+				    struct net_device *dev);
 static irqreturn_t depca_interrupt(int irq, void *dev_id);
 static int depca_close(struct net_device *dev);
 static int depca_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
@@ -928,7 +929,8 @@ static void depca_tx_timeout(struct net_device *dev)
 /*
 ** Writes a socket buffer to TX descriptor ring and starts transmission
 */
-static int depca_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t depca_start_xmit(struct sk_buff *skb,
+				    struct net_device *dev)
 {
 	struct depca_private *lp = netdev_priv(dev);
 	u_long ioaddr = dev->base_addr;