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/lance.c b/drivers/net/lance.c
index 30fd4f5..dcda303 100644
--- a/drivers/net/lance.c
+++ b/drivers/net/lance.c
@@ -300,7 +300,8 @@
 
 static int lance_open(struct net_device *dev);
 static void lance_init_ring(struct net_device *dev, gfp_t mode);
-static int lance_start_xmit(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t lance_start_xmit(struct sk_buff *skb,
+				    struct net_device *dev);
 static int lance_rx(struct net_device *dev);
 static irqreturn_t lance_interrupt(int irq, void *dev_id);
 static int lance_close(struct net_device *dev);
@@ -949,7 +950,8 @@
 }
 
 
-static int lance_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t lance_start_xmit(struct sk_buff *skb,
+				    struct net_device *dev)
 {
 	struct lance_private *lp = dev->ml_priv;
 	int ioaddr = dev->base_addr;