neoverse-rd/rdv3r1: enable atu mmio

ATU MMIO service is used by PCIe setup module to access IO manager
block configuration in AP's address space. Add the configuration file
for ATU MMIO module and enable the build for scp_ram firmware.

Signed-off-by: Lokesh B V <Lokesh.BV@Arm.com>
Change-Id: If480e72995a5b1255a87f909ac43408f8dc15f04