staging: visornic: fix visornic_xmit()'s return type

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type, but the implementation in this
driver returns an 'int'.

Fix this by returning 'netdev_tx_t' in this driver too.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visornic/visornic_main.c

@@ -849,7 +849,7 @@ static bool vnic_hit_low_watermark(struct visornic_devdata *devdata,
  *
  * Return: NETDEV_TX_OK.
  */
-static int visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
+static netdev_tx_t visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct visornic_devdata *devdata;
 	int len, firstfraglen, padlen;