net: convert remaining non-symbolic return values in ndo_start_xmit() functions

This patch converts the remaining occurences of raw return values to their
symbolic counterparts in ndo_start_xmit() functions that were missed by the
previous automatic conversion.

Additionally code that assumed the symbolic value of NETDEV_TX_OK to be zero
is changed to explicitly use NETDEV_TX_OK.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tokenring/smctr.c b/drivers/net/tokenring/smctr.c
index 54ad4ed..6515894 100644
--- a/drivers/net/tokenring/smctr.c
+++ b/drivers/net/tokenring/smctr.c
@@ -4609,7 +4609,7 @@
         if(tp->QueueSkb > 0)
 		netif_wake_queue(dev);
 		
-        return (0);
+        return NETDEV_TX_OK;
 }
 
 static int smctr_send_lobe_media_test(struct net_device *dev)