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/ns83820.c b/drivers/net/ns83820.c
index 940962a..1576ac0 100644
--- a/drivers/net/ns83820.c
+++ b/drivers/net/ns83820.c
@@ -1097,7 +1097,7 @@
 	if (unlikely(dev->CFG_cache & CFG_LNKSTS)) {
 		netif_stop_queue(ndev);
 		if (unlikely(dev->CFG_cache & CFG_LNKSTS))
-			return 1;
+			return NETDEV_TX_BUSY;
 		netif_start_queue(ndev);
 	}
 
@@ -1115,7 +1115,7 @@
 			netif_start_queue(ndev);
 			goto again;
 		}
-		return 1;
+		return NETDEV_TX_BUSY;
 	}
 
 	if (free_idx == dev->tx_intr_idx) {