PM: EM: Implement em_notify_pd_deleted()

PM: EM: Implement em_notify_pd_deleted()

Add the event notification infrastructure and implement the event
notification for when a performance domain is deleted (EM_CMD_PD_DELETED).

The event contains the ID of the performance domain (EM_A_PD_TABLE_PD_ID)
so the userspace can identify the changed performance domain for further
processing.

Signed-off-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://patch.msgid.link/20251020220914.320832-9-changwoo@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>