mlx4: mark napi id for gro_skb

Napi id was not marked for gro_skb, this will lead rx busy loop won't
work correctly since they stack never try to call low latency receive
method because of a zero socket napi id. Fix this by marking napi id
for gro_skb.

The transaction rate of 1 byte netperf tcp_rr gets about 50% increased
(from 20531.68 to 30610.88).

Cc: Amir Vadai <amirv@mellanox.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_rx.c

@@ -783,6 +783,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
 							     PKT_HASH_TYPE_L3);
 
 					skb_record_rx_queue(gro_skb, cq->ring);
+					skb_mark_napi_id(gro_skb, &cq->napi);
 
 					if (ring->hwtstamp_rx_filter == HWTSTAMP_FILTER_ALL) {
 						timestamp = mlx4_en_get_cqe_ts(cqe);