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/netxen/netxen_nic_main.c b/drivers/net/netxen/netxen_nic_main.c
index fab51d1..f824a39 100644
--- a/drivers/net/netxen/netxen_nic_main.c
+++ b/drivers/net/netxen/netxen_nic_main.c
@@ -63,7 +63,8 @@
 static void __devexit netxen_nic_remove(struct pci_dev *pdev);
 static int netxen_nic_open(struct net_device *netdev);
 static int netxen_nic_close(struct net_device *netdev);
-static int netxen_nic_xmit_frame(struct sk_buff *, struct net_device *);
+static netdev_tx_t netxen_nic_xmit_frame(struct sk_buff *,
+					       struct net_device *);
 static void netxen_tx_timeout(struct net_device *netdev);
 static void netxen_reset_task(struct work_struct *work);
 static void netxen_watchdog(unsigned long);
@@ -1599,7 +1600,7 @@
 	desc[2] = 0ULL;
 }
 
-static int
+static netdev_tx_t
 netxen_nic_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct netxen_adapter *adapter = netdev_priv(netdev);