Impact: fix UV boot crash

This fixes a UV bug related to generating global memory addresses
on partitioned systems. Partition systems do not have physical memory
at address 0. Instead, a chunk of high memory is remapped by the chipset
so that it appears to be at address 0. This remapping is INVISIBLE to most
of the OS. The only OS functions that need to be aware of the remaping are
functions that directly interface to the chipset. The GRU is one example.

Also, delete a couple of unused macros related to global memory addresses.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>