For the RD-INFRA-2021.02.24 release, add manifests for multiple
platforms (SGI-575, RD-N1-Edge, RD-E1-Edge, RD-N1-Edge dual chip,
RD-V1 and RD-V1 quad-chip) and update the RD-N2 platform manifest.

Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>
Change-Id: I937d35dad40e260d4c6357627fb084f67d2c3753

Signed-off-by: Tushar Khandelwal <tushar.khandelwal@arm.com>

Update the RD-N2 platform manifest file for the RD-INFRA-2021.01.25
platform software release.

Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>
Change-Id: Ic6945321f8675e07dd77f6da054c976c8ee0dc5d

Add a new manifest for RD-N2 platform that is pinned to a the most
recent release tag.

Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>