net: hns3: schedule mailbox task on system_unbound_wq

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

Currently, the mailbox task will be scheduled on the CPU who
received the interrupt, if there is a time-consuming task running
on this CPU, PF could not handle the mailbox in time, then VF will
wait for mailbox's reponse timeout.

This patch fixes it by schedule mailbox task on system_unbound_wq.

Feature or Bugfix:Bugfix
Signed-off-by: NHuazhong Tan <tanhuazhong@huawei.com>
Reviewed-by: Nlipeng <lipeng321@huawei.com>
Reviewed-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c

@@ -2448,7 +2448,7 @@ static void hclge_mbx_task_schedule(struct hclge_dev *hdev)
 {
 	if (!test_bit(HCLGE_STATE_CMD_DISABLE, &hdev->state) &&
 	    !test_and_set_bit(HCLGE_STATE_MBX_SERVICE_SCHED, &hdev->state))
-		schedule_work(&hdev->mbx_service_task);
+		queue_work(system_unbound_wq, &hdev->mbx_service_task);
 }
 
 static void hclge_reset_task_schedule(struct hclge_dev *hdev)