[PATCH v2 RFC] pasemi: Fix boot failure on 4.7-rc1

    Commit:d6a9996e84ac4beb7713e9485f4563e100a9b03e (powerpc/mm:
    vmalloc abstraction in preparation for radix) turned kernel memory
    and IO addresses from #defined constants to variables initialised
    at runtime.
    
    On PA6T systems the setup_arch machine call initialises the onboard
    PCI-e root-ports, and uses pci_io_base to do this, which is now before
    its value has been set resulting in a panic right after 'booting 
    linux via __start()'

    Move the pci_io_base initialisation to the same place as vmalloc
    ranges are set (hash__early_init_mmu()/radix__early_init_mmu())
    
    Reported-by: Christian Zigotzky [off-list ref]
    Signed-off-by: Darren Stevens [off-list ref]
    
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Tested on my AmigaOneX1000, I don't have access to a refence board system,
and our developer with one is on honeymoon.

I am hoping to follow this patch with others to reduce the size of the nemo
patch we apply, eventually I'd like to see the patch gone, but that is a 
very big job.

Kind regards
Darren