infra: update for RD-INFRA-2022.12.22 release

The RD-INFRA-2022.12.22 release adds support for the RD-N2-Cfg3 platform
which is a variant of the RD-N2 platform. In addition to this, platform
software for existing RD-N2, RD-N2-Cfg1, RD-N2-Cfg2 and RD-V2 is also
refreshed. There are few new features included in the release. Update
all this information in the platform documentation.

Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>
Change-Id: I81fb2e17c2d53577ad2e5a6f836e60c1cd39358d