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/pcnet32.c b/drivers/net/pcnet32.c
index 6859442..6d28b18 100644
--- a/drivers/net/pcnet32.c
+++ b/drivers/net/pcnet32.c
@@ -303,7 +303,8 @@
 static int pcnet32_probe1(unsigned long, int, struct pci_dev *);
 static int pcnet32_open(struct net_device *);
 static int pcnet32_init_ring(struct net_device *);
-static int pcnet32_start_xmit(struct sk_buff *, struct net_device *);
+static netdev_tx_t pcnet32_start_xmit(struct sk_buff *,
+				      struct net_device *);
 static void pcnet32_tx_timeout(struct net_device *dev);
 static irqreturn_t pcnet32_interrupt(int, void *);
 static int pcnet32_close(struct net_device *);
@@ -2481,7 +2482,8 @@
 	spin_unlock_irqrestore(&lp->lock, flags);
 }
 
-static int pcnet32_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t pcnet32_start_xmit(struct sk_buff *skb,
+				      struct net_device *dev)
 {
 	struct pcnet32_private *lp = netdev_priv(dev);
 	unsigned long ioaddr = dev->base_addr;