net: convert remaining non-symbolic return values in ndo_start_xmit() functions

This patch converts the remaining occurences of raw return values to their
symbolic counterparts in ndo_start_xmit() functions that were missed by the
previous automatic conversion.

Additionally code that assumed the symbolic value of NETDEV_TX_OK to be zero
is changed to explicitly use NETDEV_TX_OK.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ni52.c b/drivers/net/ni52.c
index 77d44a0..a0ac5d4 100644
--- a/drivers/net/ni52.c
+++ b/drivers/net/ni52.c
@@ -1183,7 +1183,7 @@
 
 	if (skb->len > XMIT_BUFF_SIZE) {
 		printk(KERN_ERR "%s: Sorry, max. framelength is %d bytes. The length of your frame is %d bytes.\n", dev->name, XMIT_BUFF_SIZE, skb->len);
-		return 0;
+		return NETDEV_TX_OK;
 	}
 
 	netif_stop_queue(dev);
@@ -1267,7 +1267,7 @@
 	}
 	dev_kfree_skb(skb);
 #endif
-	return 0;
+	return NETDEV_TX_OK;
 }
 
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