tools/power/turbostat: Add skeleton support for cstate enumeration

Add skeleton support for cstate enumeration.

Note that the previous logic may override the cstate setting for
multiple times for different reasons. The conversion to new cstate
enumeration must be done step by step following the previous code
order strictly.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>