tools/power turbostat: Add early support for PMT counters

Allows users to read Intel PMT (Platform Monitoring Technology)
counters, providing interface similar to one used to add MSR and perf
counters. Because PMT is exposed as a raw MMIO range, without metadata,
user has to supply the necessary information to find and correctly
display the requested counter.
Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>