Drivers:hv: Fix a bug in vmbus_driver_unregister()

The function vmbus_exists() was introduced recently to deal with cases where
the vmbus driver failed to initialize and yet other Hyper-V drivers attempted
to register with the vmbus bus driver. This patch introduced a bug where
vmbus_driver_unregister() would fail to unregister the driver. This patch
fixes the problem.
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: NFuzhou Chen <fuzhouch@microsoft.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/hv/vmbus_drv.c

@@ -627,10 +627,7 @@ void vmbus_driver_unregister(struct hv_driver *hv_driver)
 	pr_info("unregistering driver %s\n", hv_driver->name);
 
 	if (!vmbus_exists())
-		return;
-
-	driver_unregister(&hv_driver->driver);
-
+		driver_unregister(&hv_driver->driver);
 }
 EXPORT_SYMBOL_GPL(vmbus_driver_unregister);