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/ni52.c b/drivers/net/ni52.c
index a0ac5d4..bd0ac69 100644
--- a/drivers/net/ni52.c
+++ b/drivers/net/ni52.c
@@ -170,7 +170,7 @@
 static irqreturn_t ni52_interrupt(int irq, void *dev_id);
 static int     ni52_open(struct net_device *dev);
 static int     ni52_close(struct net_device *dev);
-static int     ni52_send_packet(struct sk_buff *, struct net_device *);
+static netdev_tx_t ni52_send_packet(struct sk_buff *, struct net_device *);
 static struct  net_device_stats *ni52_get_stats(struct net_device *dev);
 static void    set_multicast_list(struct net_device *dev);
 static void    ni52_timeout(struct net_device *dev);
@@ -1173,7 +1173,8 @@
  * send frame
  */
 
-static int ni52_send_packet(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ni52_send_packet(struct sk_buff *skb,
+				    struct net_device *dev)
 {
 	int len, i;
 #ifndef NO_NOPCOMMANDS