s390/pci: only add specific device in zpci_bus_scan_device()

As the name suggests zpci_bus_scan_device() is used to scan a specific
device and thus pci_bus_add_device() for that device is sufficient.
Furthermore move this call inside the rescan/remove locking.
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20230306151014.60913-3-schnelle@linux.ibm.comSigned-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/pci/pci_bus.c

@@ -87,9 +87,8 @@ int zpci_bus_scan_device(struct zpci_dev *zdev)
 	if (!pdev)
 		return -ENODEV;
 
-	pci_bus_add_device(pdev);
 	pci_lock_rescan_remove();
-	pci_bus_add_devices(zdev->zbus->bus);
+	pci_bus_add_device(pdev);
 	pci_unlock_rescan_remove();
 
 	return 0;