PCI hotplug: acpiphp: use generic pci_configure_slot()
Use the generic pci_configure_slot() rather than the acpiphp-specific
decode_hpp() and program_hpp().
Unlike the previous acpiphp-specific code, pci_configure_slot() programs
PCIe settings when an _HPX method provides them, so acpiphp-managed PCIe
devices can now be configured.