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/ewrk3.c b/drivers/net/ewrk3.c
index 9c51bc8..b2a5ec8 100644
--- a/drivers/net/ewrk3.c
+++ b/drivers/net/ewrk3.c
@@ -298,7 +298,7 @@
    ** Public Functions
  */
 static int ewrk3_open(struct net_device *dev);
-static int ewrk3_queue_pkt(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t ewrk3_queue_pkt(struct sk_buff *skb, struct net_device *dev);
 static irqreturn_t ewrk3_interrupt(int irq, void *dev_id);
 static int ewrk3_close(struct net_device *dev);
 static void set_multicast_list(struct net_device *dev);
@@ -764,7 +764,7 @@
 /*
    ** Writes a socket buffer to the free page queue
  */
-static int ewrk3_queue_pkt (struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ewrk3_queue_pkt(struct sk_buff *skb, struct net_device *dev)
 {
 	struct ewrk3_private *lp = netdev_priv(dev);
 	u_long iobase = dev->base_addr;