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/cxgb3/adapter.h b/drivers/net/cxgb3/adapter.h
index 74723f2..2b1aea6 100644
--- a/drivers/net/cxgb3/adapter.h
+++ b/drivers/net/cxgb3/adapter.h
@@ -309,7 +309,7 @@
 void t3_free_sge_resources(struct adapter *adap);
 void t3_sge_err_intr_handler(struct adapter *adapter);
 irq_handler_t t3_intr_handler(struct adapter *adap, int polling);
-int t3_eth_xmit(struct sk_buff *skb, struct net_device *dev);
+netdev_tx_t t3_eth_xmit(struct sk_buff *skb, struct net_device *dev);
 int t3_mgmt_tx(struct adapter *adap, struct sk_buff *skb);
 void t3_update_qset_coalesce(struct sge_qset *qs, const struct qset_params *p);
 int t3_sge_alloc_qset(struct adapter *adapter, unsigned int id, int nports,