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/sundance.c b/drivers/net/sundance.c
index d09be48..e13685a 100644
--- a/drivers/net/sundance.c
+++ b/drivers/net/sundance.c
@@ -415,7 +415,7 @@
 static void netdev_timer(unsigned long data);
 static void tx_timeout(struct net_device *dev);
 static void init_ring(struct net_device *dev);
-static int  start_tx(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t start_tx(struct sk_buff *skb, struct net_device *dev);
 static int reset_tx (struct net_device *dev);
 static irqreturn_t intr_handler(int irq, void *dev_instance);
 static void rx_poll(unsigned long data);
@@ -1053,7 +1053,7 @@
 	return;
 }
 
-static int
+static netdev_tx_t
 start_tx (struct sk_buff *skb, struct net_device *dev)
 {
 	struct netdev_private *np = netdev_priv(dev);