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/pcmcia/axnet_cs.c b/drivers/net/pcmcia/axnet_cs.c
index 15b8fe6..0e38d80 100644
--- a/drivers/net/pcmcia/axnet_cs.c
+++ b/drivers/net/pcmcia/axnet_cs.c
@@ -1130,7 +1130,7 @@
 		outb_p(ENISR_ALL, e8390_base + EN0_IMR);
 		spin_unlock_irqrestore(&ei_local->page_lock, flags);
 		dev->stats.tx_errors++;
-		return 1;
+		return NETDEV_TX_BUSY;
 	}
 
 	/*