feat(fvp): define ns memory in the SPMC manifest

feat(fvp): define ns memory in the SPMC manifest

The SPMC (Hafnium) looks for secure and non-secure ranges
in its manifest.
Those relate with ranges that can be used by SPs in their
FF-A manifests.
The NS memory that is not used by SPs will be assigned
to the NWd, for it to share memory with SPs as needed.
Thus, this limits the memory the NWd can share with SPs,
to prevent NWD VMs from sharing memory that belongs
to other critical components.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: Iad03eb138a57068fbb18c53141bdf6bf9c171b28