powercap / RAPL: further relax energy counter checks

Energy counters may roll slowly for some RAPL domains, checking all
of them can be time consuming and takes unpredictable amount of time.
Therefore, we relax the sanity check by only checking availability of the
MSRs and non-zero value of the energy status counters. It has been shown
sufficient for all the platforms tested to filter out inactive domains.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>