xen-netback: return correct ethtool stats

Use correct pointer arithmetic to get the pointer to each stat.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/interface.c

@@ -340,12 +340,11 @@ static void xenvif_get_ethtool_stats(struct net_device *dev,
 	unsigned int num_queues = vif->num_queues;
 	int i;
 	unsigned int queue_index;
-	struct xenvif_stats *vif_stats;
 
 	for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++) {
 		unsigned long accum = 0;
 		for (queue_index = 0; queue_index < num_queues; ++queue_index) {
-			vif_stats = &vif->queues[queue_index].stats;
+			void *vif_stats = &vif->queues[queue_index].stats;
 			accum += *(unsigned long *)(vif_stats + xenvif_stats[i].offset);
 		}
 		data[i] = accum;