PCI: endpoint: Fix missing destroy_workqueue()

Add the missing destroy_workqueue() before return from
pci_epf_test_init() in the error handling case and add
destroy_workqueue() in pci_epf_test_exit().

Link: https://lore.kernel.org/r/20210331084012.2091010-1-yangyingliang@huawei.com
Fixes: 349e7a85b2 ("PCI: endpoint: functions: Add an EP function to test PCI")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/endpoint/functions/pci-epf-test.c

@@ -925,6 +925,7 @@ static int __init pci_epf_test_init(void)
 
 	ret = pci_epf_register_driver(&test_driver);
 	if (ret) {
+		destroy_workqueue(kpcitest_workqueue);
 		pr_err("Failed to register pci epf test driver --> %d\n", ret);
 		return ret;
 	}
@@ -935,6 +936,8 @@ module_init(pci_epf_test_init);
 
 static void __exit pci_epf_test_exit(void)
 {
+	if (kpcitest_workqueue)
+		destroy_workqueue(kpcitest_workqueue);
 	pci_epf_unregister_driver(&test_driver);
 }
 module_exit(pci_epf_test_exit);