i40e: stop the service task at shutdown

Stop the service task in the shutdown handler, preventing it from
accessing the admin queue after it had been closed. This fixes a panic
that could occur when the system was shut down with a lot of VFs
enabled.

Change-ID: I286735e3842de472385bbf7ad68d30331e508add
Signed-off-by: NMitch Williams <mitch.a.williams@intel.com>
Tested-by: NJim Young <james.m.young@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -9736,6 +9736,8 @@ static int i40e_suspend(struct pci_dev *pdev, pm_message_t state)
 
 	set_bit(__I40E_SUSPENDED, &pf->state);
 	set_bit(__I40E_DOWN, &pf->state);
+	del_timer_sync(&pf->service_timer);
+	cancel_work_sync(&pf->service_task);
 	rtnl_lock();
 	i40e_prep_for_reset(pf);
 	rtnl_unlock();