perf/x86: Move Intel specific code to intel_pmu_init()

There is some Intel specific code in the generic x86 path. Move it to
intel_pmu_init().

Since p4 and p6 pmus don't have fixed counters we may skip the check
in case such a pmu is detected.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1340217996-2254-3-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>