product/rdn2: add helper functions to obtain platform topology

Functions to obtain the platform topology information such as core
count, cluster count help in adding configuration data dynamically and
can be used by modules to add the configuration data dynamically.

Change-Id: Iadb7c7bb77c290517e2b596b71d3a3fed3d3c927
Signed-off-by: Aditya Angadi <aditya.angadi@arm.com>