scmi: SCMI System Power requestor and UT
Created by: leandro-arm
The purpose of this patch is to introduce the System Power Requestor module.
At this time, it is designed to work with a single element and is being utilised by the SCMI System Power module.
The module takes an SCMI System Power command and forwards it to its element, in such a way that it is received by them as if it were purely a System Power command.