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/atp.c b/drivers/net/atp.c
index 4beacc9..9043294 100644
--- a/drivers/net/atp.c
+++ b/drivers/net/atp.c
@@ -199,7 +199,8 @@
 static void hardware_init(struct net_device *dev);
 static void write_packet(long ioaddr, int length, unsigned char *packet, int pad, int mode);
 static void trigger_send(long ioaddr, int length);
-static int	atp_send_packet(struct sk_buff *skb, struct net_device *dev);
+static netdev_tx_t atp_send_packet(struct sk_buff *skb,
+				   struct net_device *dev);
 static irqreturn_t atp_interrupt(int irq, void *dev_id);
 static void net_rx(struct net_device *dev);
 static void read_block(long ioaddr, int length, unsigned char *buffer, int data_mode);
@@ -552,7 +553,8 @@
 	dev->stats.tx_errors++;
 }
 
-static int atp_send_packet(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t atp_send_packet(struct sk_buff *skb,
+				   struct net_device *dev)
 {
 	struct net_local *lp = netdev_priv(dev);
 	long ioaddr = dev->base_addr;