Revert "tools/power turbostat: stop migrating, unless '-m'"

This reverts commit c91fc851.

That change caused a C6 and PC6 residency regression on large idle systems.

Users also complained about new output indicating jitter:

turbostat: cpu6 jitter 3794 9142

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: 4.13+ <stable@vger.kernel.org> # v4.13+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>