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/wan/cycx_x25.c b/drivers/net/wan/cycx_x25.c
index f525f9f..4ae9bd2 100644
--- a/drivers/net/wan/cycx_x25.c
+++ b/drivers/net/wan/cycx_x25.c
@@ -663,7 +663,7 @@
 free_packet:
 	dev_kfree_skb(skb);
 
-	return 0;
+	return NETDEV_TX_OK;
 }
 
 /* Get Ethernet-style interface statistics.