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/include/linux/arcdevice.h b/include/linux/arcdevice.h
index cd4bcb6..7d650a0 100644
--- a/include/linux/arcdevice.h
+++ b/include/linux/arcdevice.h
@@ -337,7 +337,8 @@
 
 int arcnet_open(struct net_device *dev);
 int arcnet_close(struct net_device *dev);
-int arcnet_send_packet(struct sk_buff *skb, struct net_device *dev);
+netdev_tx_t arcnet_send_packet(struct sk_buff *skb,
+				     struct net_device *dev);
 void arcnet_timeout(struct net_device *dev);
 
 #endif				/* __KERNEL__ */