pci_get_bus_and_slot() is restrictive such that it assumes domain=0 as
where a PCI device is present. This restricts the device drivers to be
reused for other domain numbers.

Getting ready to remove pci_get_bus_and_slot() function in favor of
pci_get_domain_bus_and_slot().

Use domain number of 0 as the domain number is not available in struct
irq_routing_table.
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>