x86/UV: Add GRU distributed mode mappings

x86/UV: Add GRU distributed mode mappings

GRU hardware will support an optional distributed mode that will
allow  per-node address mapping of local GRU space, as opposed
to mapping all GRU hardware to the same contiguous high space.

If GRU distributed mode is selected, setup per-node page table
mappings.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Cc: Alexander Gordeev <agordeev@redhat.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Mike Travis <travis@sgi.com>
Link: http://lkml.kernel.org/r/20130529155609.GB22917@sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>