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.

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