powercap: intel_rapl: Support per Interface primitive information

RAPL primitive information is Interface specific.

Although current MSR and MMIO Interface share the same RAPL primitives,
new Interface like TPMI has its own RAPL primitive information.

Save the primitive information in the Interface private structure.

Plus, using variant name "rp" for struct rapl_primitive_info is
confusing because "rp" is also used for struct rapl_package.
Use "rpi" as the variant name for struct rapl_primitive_info, and rename
the previous rpi[] array to avoid conflict.

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>