mlx4: add a new xmit_more counter

ethtool -S reports a new counter, tracking number of time doorbell
was not triggered, because skb->xmit_more was set.

$ ethtool -S eth0 | egrep "tx_packet|xmit_more"
     tx_packets: 2413288400
     xmit_more: 666121277

I merged the tso_packet false sharing avoidance in this patch as well.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index adedc47..0c50125 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -840,7 +840,7 @@
 		 * note that we already verified that it is linear */
 		memcpy(tx_desc->lso.header, skb->data, lso_header_size);
 
-		priv->port_stats.tso_packets++;
+		ring->tso_packets++;
 		i = ((skb->len - lso_header_size) / skb_shinfo(skb)->gso_size) +
 			!!((skb->len - lso_header_size) % skb_shinfo(skb)->gso_size);
 		tx_info->nr_bytes = skb->len + (i - 1) * lso_header_size;
@@ -910,6 +910,8 @@
 			wmb();
 			iowrite32be(ring->doorbell_qpn,
 				    ring->bf.uar->map + MLX4_SEND_DOORBELL);
+		} else {
+			ring->xmit_more++;
 		}
 	}