power_domain: Add check for get_last_core_pd_id
Created by: leandro-arm
This patch implements a validation check such that when the get_last_core_pd_id() function is called by the driver, the module returns an error if the system is not performing system_supend.
Change-Id: Ied3a2f17b2fb471933232c8209e4d3048c4a1e8b Signed-off-by: Leandro Belli leandro.belli@arm.com