kvm tools: Don't disable PerfMon if host does not support it

KVM provides of PMU with architectural events, so don't disable
the NMI drivent based performance events when they are available
on the host.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Asias He <asias.hejun@gmail.com>