Platform/Sgi: enable firmware-first error handling

Enable the use of HEST table generation protocol, GHES error source
descriptor protocol on ARM Neoverse Reference Design platforms.
This enables the framework to support firmware first error handling on
ARM Neoverse Reference Design platforms.

Co-authored-by: Thomas Abraham <thomas.abraham@arm.com>
Signed-off-by: Omkar Anand Kulkarni <omkar.kulkarni@arm.com>
Change-Id: Ie6fd56aca13042aaa65a959c53eedb55913d9cdd