net: use symbolic values for ndo_start_xmit() return codes

Convert magic values 1 and -1 to NETDEV_TX_BUSY and NETDEV_TX_LOCKED respectively.

0 (NETDEV_TX_OK) is not changed to keep the noise down, except in very few cases
where its in direct proximity to one of the other values.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pcmcia/fmvj18x_cs.c

@@ -877,7 +877,7 @@ static int fjn_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (length > ETH_FRAME_LEN) {
 	    printk(KERN_NOTICE "%s: Attempting to send a large packet"
 		   " (%d bytes).\n", dev->name, length);
-	    return 1;
+	    return NETDEV_TX_BUSY;
 	}
 
 	DEBUG(4, "%s: Transmitting a packet of length %lu.\n",