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/ieee802154/fakehard.c b/drivers/ieee802154/fakehard.c
index c1c9697..96a2959 100644
--- a/drivers/ieee802154/fakehard.c
+++ b/drivers/ieee802154/fakehard.c
@@ -257,7 +257,8 @@
 	return 0;
 }
 
-static int ieee802154_fake_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ieee802154_fake_xmit(struct sk_buff *skb,
+					      struct net_device *dev)
 {
 	skb->iif = dev->ifindex;
 	skb->dev = dev;