tools/power turbostat: Add reading aperf and mperf via perf API

By using the perf API we spend less time in between the reads of the
counters, resulting in more accurate calculations of the dependent
metrics.

Using perf API is also usually faster overall, although cache miss, if
we get one, is more costly when using perf vs MSR driver.

We would fallback to the msr reads if the sysfs isn't there or when in
--no-perf mode.
Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>