ehea: Fix workqueue handling

Fix: Workqueue ehea_driver_wq was not destroyed

Signed-off-by: Thomas Klein <tklein@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/ehea/ehea_main.c

@@ -3099,6 +3099,7 @@ out:
 
 static void __exit ehea_module_exit(void)
 {
+	destroy_workqueue(ehea_driver_wq);
 	driver_remove_file(&ehea_driver.driver, &driver_attr_capabilities);
 	ibmebus_unregister_driver(&ehea_driver);
 	ehea_destroy_busmap();