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>
diff --git a/drivers/net/smc9194.c b/drivers/net/smc9194.c
index 9a7973a..e02471b 100644
--- a/drivers/net/smc9194.c
+++ b/drivers/net/smc9194.c
@@ -503,7 +503,7 @@
 		/* THIS SHOULD NEVER HAPPEN. */
 		dev->stats.tx_aborted_errors++;
 		printk(CARDNAME": Bad Craziness - sent packet while busy.\n" );
-		return 1;
+		return NETDEV_TX_BUSY;
 	}
 	lp->saved_skb = skb;