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/eth16i.c b/drivers/net/eth16i.c
index 97d5205..71bfeec 100644
--- a/drivers/net/eth16i.c
+++ b/drivers/net/eth16i.c
@@ -405,7 +405,7 @@
 static void    eth16i_eeprom_cmd(int ioaddr, unsigned char command);
 static int     eth16i_open(struct net_device *dev);
 static int     eth16i_close(struct net_device *dev);
-static int     eth16i_tx(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t eth16i_tx(struct sk_buff *skb, struct net_device *dev);
 static void    eth16i_rx(struct net_device *dev);
 static void    eth16i_timeout(struct net_device *dev);
 static irqreturn_t eth16i_interrupt(int irq, void *dev_id);
@@ -1053,7 +1053,7 @@
 	netif_wake_queue(dev);
 }
 
-static int eth16i_tx(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t eth16i_tx(struct sk_buff *skb, struct net_device *dev)
 {
 	struct eth16i_local *lp = netdev_priv(dev);
 	int ioaddr = dev->base_addr;