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/znet.c b/drivers/net/znet.c
index 0a6992d..7f9e141 100644
--- a/drivers/net/znet.c
+++ b/drivers/net/znet.c
@@ -546,7 +546,7 @@
 
 	if (length < ETH_ZLEN) {
 		if (skb_padto(skb, ETH_ZLEN))
-			return 0;
+			return NETDEV_TX_OK;
 		length = ETH_ZLEN;
 	}
 
@@ -600,7 +600,7 @@
 		  printk(KERN_DEBUG "%s: Transmitter queued, length %d.\n", dev->name, length);
 	}
 	dev_kfree_skb(skb);
-	return 0;
+	return NETDEV_TX_OK;
 }
 
 /* The ZNET interrupt handler. */