s390/pci: cleanup resources only if necessary

commit 02368b7c upstream.

It's currently safe to call zpci_cleanup_bus_resources() even if the
resources were never created but it makes no sense so check
zdev->has_resources before we call zpci_cleanup_bus_resources() in
zpci_release_device().

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>