PCI hotplug: pciehp: use generic pci_configure_slot()

Use the generic pci_configure_slot() rather than the PCIe-specific
program_fw_provided_values().

Unlike the previous pciehp-specific code, we now walk through subordinate
devices even if there are no settings for the parent.  This should be
harmless because we won't change anything unless we discover firmware
settings farther down.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>