pci_fixup_irqs() is problematic because:

  - it's called when we enumerate a host bridge, so we don't fixup IRQs for
    hot-added PCI devices, and

  - it fixes up IRQs for all PCI devices in the system, so if we call it
    multiple times, e.g., if we have several host controllers, we may
    reallocate an IRQ for a device after a driver has already claimed it.

We plan to replace pci_fixup_irqs() soon, but we still need it on ARM
because we don't have any other generic method for doing this.

On ARM64, we don't need pci_fixup_irqs() because we do IRQ setup when we
bind a driver to the device (in the pci_device_probe() ->
pcibios_alloc_irq() path).

pci-host-common.c is currently only used on ARM and ARM64.  In principle,
it could be used on x86, and we wouldn't want pci_fixup_irqs() there
either, because x86 does IRQ setup in the pci_enable_device() path.

[bhelgaas: changelog, use #ifdef ARM, not #ifndef ARM64]
Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
Reviewed-by: Zhou Wang <wangzhou1@hisilicon.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>