[RFC/PATCH 1/2] pci: Add ability to mmap legacy_io on some platforms

[Luck, Tony]

> I didn't have a chance to test that I didn't break ia64, so I would
> be if somebody could give it a spin there ! Thanks !

All my ia64 config variations still build cleanly with
these two patches applied.  I booted a couple of systems
too with no obvious ill-effects.

I have the same set of "legacy_io" and "legacy_mem" files
in /sys/class/pci_bus/xxxx:xx/ that I had before applying
these patches.  I'm not sure how to test that they still
"work".

-Tony