Changes for SCMI-v2 & SCP-v2.8

Created by: nicola-mazzucato-arm

This PR contains fixes/changes for: SCMI v2.0: base protocol and power domain protocol SCP-v2.8: Release notes for v.2.8.0

Note that this PR is likely to fail the github tests, because related changes for automated ci are not yet merged (series: https://review.trustedfirmware.org/c/ci/tf-a-ci-scripts/+/9487). However, internal tests have passed.