xen-pcifront: don't use flush_scheduled_work()

flush_scheduled_work() is scheduled for deprecation.  Cancel ->op_work
directly instead.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Ryan Wilson <hap9@epoch.ncsc.mil>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/pci/xen-pcifront.c

@@ -733,8 +733,7 @@ static void free_pdev(struct pcifront_device *pdev)
 
 	pcifront_free_roots(pdev);
 
-	/*For PCIE_AER error handling job*/
-	flush_scheduled_work();
+	cancel_work_sync(&pdev->op_work);
 
 	if (pdev->irq >= 0)
 		unbind_from_irqhandler(pdev->irq, pdev);