perf, x86: Add Nehalem programming quirk to Westmere

According to the Xeon-5600 errata the Westmere suffers the same PMU
programming bug as the original Nehalem did.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>