feat(rd1ae): introduce Arm RD-1 AE platform

Create a new platform for the RD-1 AE automotive FVP.
This platform contains:
 * Neoverse-V3AE, Arm9.2-A application processor
 * A GICv4-compatible GIC-720AE
 * 128 MB of SRAM, of which 1 MB is reserved for TF-A

and BL2 runs at ELmax (EL3).

Additionally, this commit updates the maintainers.rst file and
the changelog.yaml to add scope for RD-1 AE variants.

Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Signed-off-by: Divin Raj <divin.raj@arm.com>
Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Change-Id: I9ae64b3f05a52653ebd1d334b15b7f21821264e2
8 files changed