powercap: intel_rapl: Introduce RAPL I/F type

Different RAPL Interfaces may have different primitive information and
rapl_defaults calls.

To better distinguish this difference in the RAPL framework code,
introduce a new enum to represent different types of RAPL Interfaces.

No functional change.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Wang Wendy <wendy.wang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>