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/irda/sir_dev.c b/drivers/net/irda/sir_dev.c
index d940809..fd0796c 100644
--- a/drivers/net/irda/sir_dev.c
+++ b/drivers/net/irda/sir_dev.c
@@ -607,7 +607,7 @@
 				 * stopped so the network layer will retry after the
 				 * fsm completes and wakes the queue.
 				 */
-				 return 1;
+				 return NETDEV_TX_BUSY;
 			}
 			else if (unlikely(err)) {
 				/* other fatal error - forget the speed change and