feat(rdv3r1): Add initial platform support

RD-V3-R1 and RD-V3-R1-Cfg1 Fixed Virtual Platforms are Arm Neoverse
Reference Design platforms with ARMv9 RME enabled CPUs and 2 DRAM banks.
Add initial platform support by adding the required platform configuration
file that includes RMM size, number of xlat table context, granule
information and maximum CPUs supported.

Signed-off-by: Lokesh B V <Lokesh.BV@Arm.com>
Change-Id: I5c5ac99c1b079d881d5a6724832a879df291200f