From: Anton Blanchard <anton@samba.org>
      Rusty Russell <rusty@rustcorp.com.au>

The iSeries has an arch-specific mapping from physical <-> absolute
addresses.  Fortunately this is only used in a few places.  However, the
following arch-specific macros/functions are provided in addition to the
standard macros:

	__a2p()
	__a2v()
	__p2a()
	__p2v()
	__v2a()
	__v2p()
	absolute_to_phys()
	phys_to_absolute()
	virt_to_absolute()
	absolute_to_virt()

Reduce them to these, with slightly shorter names, and taking either pointers
or unsigned long (as per __va and __pa) rather than making the caller cast:

	abs_to_phys()
	phys_to_abs()

And helper macros:

	virt_to_abs()
	abs_to_virt()

As is standard, virtual addresses are returned as void *, physical and
absolute as unsigned long.

Note that the change the iSeries_setup is a little subtle: ea is set to
__va(pa) above, so "phys_to_abs(pa)" is the same as "virt_to_abs(ea)".

Also, REALADDR is renamed to ISERIES_HV_ADDR and used in a couple of places
where appropriate.