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>
diff --git a/drivers/net/pcnet32.c b/drivers/net/pcnet32.c
index 1c35e1d..955a87a 100644
--- a/drivers/net/pcnet32.c
+++ b/drivers/net/pcnet32.c
@@ -2536,7 +2536,7 @@
 		netif_stop_queue(dev);
 	}
 	spin_unlock_irqrestore(&lp->lock, flags);
-	return 0;
+	return NETDEV_TX_OK;
 }
 
 /* The PCNET32 interrupt handler. */