feat: secure hafnium build fro RD Fremont platform

RD (Reference Design) is a collection of resources to provide a
representative view of typical compute subsystems that can be designed
and implemented using specific generations of Arm IP.
RD-Fremont supports S-EL2 and needs S-EL2 SPMC/Hafnium to manage its
secure partitions running at S-EL0.

Change-Id: I1aebd791757e555cd38ad3240d9a99c77de4ff14
Signed-off-by: Nishant Sharma <nishant.sharma@arm.com>