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/ariadne.c b/drivers/net/ariadne.c
index 47d976c..c35af3e 100644
--- a/drivers/net/ariadne.c
+++ b/drivers/net/ariadne.c
@@ -115,7 +115,8 @@
 
 static int ariadne_open(struct net_device *dev);
 static void ariadne_init_ring(struct net_device *dev);
-static int ariadne_start_xmit(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t ariadne_start_xmit(struct sk_buff *skb,
+				      struct net_device *dev);
 static void ariadne_tx_timeout(struct net_device *dev);
 static int ariadne_rx(struct net_device *dev);
 static void ariadne_reset(struct net_device *dev);
@@ -589,7 +590,8 @@
 }
 
 
-static int ariadne_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ariadne_start_xmit(struct sk_buff *skb,
+				      struct net_device *dev)
 {
     struct ariadne_private *priv = netdev_priv(dev);
     volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;