x86, perf: Add constraints for architectural PMU

x86, perf: Add constraints for architectural PMU

The v1 PMU does not have any fixed counters.  Using the v2 constraints,
which do have fixed counters, causes an additional choice to be present
in the weight calculation, but not when actually scheduling the event,
leading to an event being not scheduled at all.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1309362157-6596-3-git-send-email-avi@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>