netdev: convert bulk of drivers to netdev_tx_t

In a couple of cases collapse some extra code like:
   int retval = NETDEV_TX_OK;
   ...
   return retval;
into
   return NETDEV_TX_OK;

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index a7d14aa..9d5c178 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -5135,7 +5135,8 @@
 /* hard_start_xmit for devices that don't have any bugs and
  * support TG3_FLG2_HW_TSO_2 only.
  */
-static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t tg3_start_xmit(struct sk_buff *skb,
+				  struct net_device *dev)
 {
 	struct tg3 *tp = netdev_priv(dev);
 	u32 len, entry, base_flags, mss;
@@ -5251,7 +5252,8 @@
 	return NETDEV_TX_OK;
 }
 
-static int tg3_start_xmit_dma_bug(struct sk_buff *, struct net_device *);
+static netdev_tx_t tg3_start_xmit_dma_bug(struct sk_buff *,
+					  struct net_device *);
 
 /* Use GSO to workaround a rare TSO bug that may be triggered when the
  * TSO header is greater than 80 bytes.
@@ -5290,7 +5292,8 @@
 /* hard_start_xmit for devices that have the 4G bug and/or 40-bit bug and
  * support TG3_FLG2_HW_TSO_1 or firmware TSO only.
  */
-static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t tg3_start_xmit_dma_bug(struct sk_buff *skb,
+					  struct net_device *dev)
 {
 	struct tg3 *tp = netdev_priv(dev);
 	u32 len, entry, base_flags, mss;