net: use NETDEV_TX_OK instead of 0 in ndo_start_xmit() functions

This patch is the result of an automatic spatch transformation to convert
all ndo_start_xmit() return values of 0 to NETDEV_TX_OK.

Some occurences are missed by the automatic conversion, those will be
handled in a seperate patch.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/natsemi.c

@@ -2125,7 +2125,7 @@ static int start_tx(struct sk_buff *skb, struct net_device *dev)
 		printk(KERN_DEBUG "%s: Transmit frame #%d queued in slot %d.\n",
 			dev->name, np->cur_tx, entry);
 	}
-	return 0;
+	return NETDEV_TX_OK;
 }
 
 static void netdev_tx_done(struct net_device *dev)