powercap: intel_rapl: Remove unused AVERAGE_POWER primitive

powercap: intel_rapl: Remove unused AVERAGE_POWER primitive

The AVERAGE_POWER primitive and RAPL_PRIMITIVE_DERIVED flag are not
used anywhere in the code.

Remove them to simplify the primitive handling logic.

No functional changes.

Co-developed-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20260313185333.2370733-2-sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>