sfc: Do not set net_device::trans_start in self-test

Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/sfc/selftest.c

@@ -435,7 +435,6 @@ static int efx_begin_loopback(struct efx_tx_queue *tx_queue)
 			kfree_skb(skb);
 			return -EPIPE;
 		}
-		efx->net_dev->trans_start = jiffies;
 	}
 
 	return 0;