x86, UV: Correct reset_with_ipi()

x86, UV: Correct reset_with_ipi()

Fix reset_with_ipi() to look up a cpu for a blade based on the
distribution map being indexed by the potentially sparsely
numbered pnode.

This patch is critical to tlb shootdown on a partitioned UV
system, or one with nonconsecutive blade numbers.

The distribution map bits represent pnodes relative to the partition base
pnode. Previous to this patch it had been assuming bits based on 0-based,
consecutive blade ids.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Link: http://lkml.kernel.org/r/20110621122242.497700003@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>