x86: SGI UV: Fix mapping of MMIO registers

This fixes the problem of the initialization code not correctly
mapping the entire MMIO space on a UV system.  A side effect is
the map_high() interface needed to be changed to accommodate
different address and size shifts.

Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Mike Habeck <habeck@sgi.com>
Cc: <stable@kernel.org>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <4B479202.7080705@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>