perf, x86: Store perfctr msr addresses in config_base/event_base

Instead of storing the base addresses we can store the counter's msr
addresses directly in config_base/event_base of struct hw_perf_event.
This avoids recalculating the address with each msr access. The
addresses are configured one time. We also need this change to later
modify the address calculation.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1296664860-10886-5-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>