This effectively reverts 859a3f86 ("ACPI: simplify
acpi_pci_irq_add_prt() API") and d9efae36 ("ACPI: simplify
acpi_pci_irq_del_prt() API").

The reason is to disentangle these routines from the struct pci_bus.
We want to be able to add the _PRT before the struct pci_bus
exists, and delete the _PRT after we've removed the pci_bus.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NTaku Izumi <izumi.taku@jp.fujitsu.com>