net: batch of last_rx update avoidance in ethernet drivers.

None of those drivers uses last_rx for its own needs.

See 4dc89133f4 ("net: add a comment on
netdev->last_rx") for reference.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Wingman Kwok <w-kwok2@ti.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hix5hd2_gmac.c

@@ -500,7 +500,6 @@ static int hix5hd2_rx(struct net_device *dev, int limit)
 		napi_gro_receive(&priv->napi, skb);
 		dev->stats.rx_packets++;
 		dev->stats.rx_bytes += skb->len;
-		dev->last_rx = jiffies;
 next:
 		pos = dma_ring_incr(pos, RX_DESC_NUM);
 	}