x86, UV: Fix APICID shift for Westmere processors

Westmere processors use a different algorithm for
assigning APICIDs on SGI UV systems. The location of the
node number within the apicid is now a function of the
processor type.

Signed-off-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20110110195210.GA18737@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>