build(versal-net): add build config for ddr

Add build config for Versal NET platform.
The TF-A is placed and executed from DDR in this scenario.

Signed-off-by: Akshay Belsare <akshay.belsare@amd.com>
Change-Id: I44df99a9cdd0cdab53bf9005bf5b52da170f8680
2 files changed