tools/power turbostat: Support thermal throttle count print

The turbostat data is collected by end user for power evaluationit. However
it looks like we are missing enough thermal context there. Already a couple of
time we found that power management developer asking something like this:
grep -r . /sys/devices/system/cpu/cpu*/thermal_throttle/*

Print the per core thermal throttle count so as to get suffificent thermal
context.

turbostat -i 5 -s Core,CPU,CoreThr
Core	CPU	CoreThr
-	-	104
0	0	61
0	4
1	1	0
1	5
2	2	104
2	6
3	3	7
3	7

Suggested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>