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/8390.h b/drivers/net/8390.h
index 3c61d6d..3d9e8fb 100644
--- a/drivers/net/8390.h
+++ b/drivers/net/8390.h
@@ -40,7 +40,7 @@
 extern int ei_close(struct net_device *dev);
 extern irqreturn_t ei_interrupt(int irq, void *dev_id);
 extern void ei_tx_timeout(struct net_device *dev);
-extern int ei_start_xmit(struct sk_buff *skb, struct net_device *dev);
+extern netdev_tx_t ei_start_xmit(struct sk_buff *skb, struct net_device *dev);
 extern void ei_set_multicast_list(struct net_device *dev);
 extern struct net_device_stats *ei_get_stats(struct net_device *dev);
 
@@ -58,7 +58,7 @@
 extern int eip_close(struct net_device *dev);
 extern irqreturn_t eip_interrupt(int irq, void *dev_id);
 extern void eip_tx_timeout(struct net_device *dev);
-extern int eip_start_xmit(struct sk_buff *skb, struct net_device *dev);
+extern netdev_tx_t eip_start_xmit(struct sk_buff *skb, struct net_device *dev);
 extern void eip_set_multicast_list(struct net_device *dev);
 extern struct net_device_stats *eip_get_stats(struct net_device *dev);