powercap / RAPL: Add support for Ivy Bridge server

It's confirmed that RAPL works as expected on Ivy Bridge servers.
Tested against processor: Intel(R) Xeon(R) CPU E5-2697 v2 @2.70GHz

Signed-off-by: Xiaolong Wang <xiaolong.wang@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>