cns3xxx PCIe domain support

[Arnd Bergmann]

I'm working on a patch series to simplify the ARM pci-common
implementation and came across cns3xxx, which unlike the other
non-DT platforms does not partition the bus space of PCI domain
zero but instead uses the default bus range 0...255 for each
host bridge without assigning domain numbers.

Before linux-3.20, commitm c88d54ba0c3d ("CNS3xxx: Remove
artificial dependency on pci_sys_data domain."), it used to
assign a domain number, but since then, the pci-common code
just supports a single domain.

My question is: does this actually work correctly without
leading to duplicate domain/bus/device/function tuples?
Is there anything I'm missing in the code, or could it be
that the machines that Koen and Krzysztof were running
on never used more than one of the host bridges?

       Arnd