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/ibmlana.c b/drivers/net/ibmlana.c
index 448098d..090a6d3 100644
--- a/drivers/net/ibmlana.c
+++ b/drivers/net/ibmlana.c
@@ -812,7 +812,7 @@
 
 /* transmit a block. */
 
-static int ibmlana_tx(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ibmlana_tx(struct sk_buff *skb, struct net_device *dev)
 {
 	ibmlana_priv *priv = netdev_priv(dev);
 	int tmplen, addr;