net: ena: use setup_timer() and mod_timer()

Use setup_timer() instead of init_timer(), being the preferred/standard
way to set a timer up.

Also, quoting the mod_timer() function comment:
-> mod_timer() is a more efficient way to update the expire field of an
   active timer (if the timer is inactive it will be activated).

Use setup_timer and mod_timer to setup and arm a timer, to make the code
cleaner and easier to read.
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -3013,12 +3013,9 @@ static int ena_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	adapter->last_keep_alive_jiffies = jiffies;
 
-	init_timer(&adapter->timer_service);
-	adapter->timer_service.expires = round_jiffies(jiffies + HZ);
-	adapter->timer_service.function = ena_timer_service;
-	adapter->timer_service.data = (unsigned long)adapter;
-
-	add_timer(&adapter->timer_service);
+	setup_timer(&adapter->timer_service, ena_timer_service,
+		    (unsigned long)adapter);
+	mod_timer(&adapter->timer_service, round_jiffies(jiffies + HZ));
 
 	dev_info(&pdev->dev, "%s found at mem %lx, mac addr %pM Queues %d\n",
 		 DEVICE_NAME, (long)pci_resource_start(pdev, 0),