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/irda/via-ircc.c b/drivers/net/irda/via-ircc.c
index 62ba94b..36a6074 100644
--- a/drivers/net/irda/via-ircc.c
+++ b/drivers/net/irda/via-ircc.c
@@ -832,7 +832,7 @@
 	__u32 speed;
 
 	self = netdev_priv(dev);
-	IRDA_ASSERT(self != NULL, return 0;);
+	IRDA_ASSERT(self != NULL, return NETDEV_TX_OK;);
 	iobase = self->io.fir_base;
 
 	netif_stop_queue(dev);