Platform/Sgi: prepare SRAT, HMAT table

Get remote memory node details from  Remote Memory HOB list.
Prepare SRAT table with both Local memory, remote memory blocks,
along with other necessary details.

Prepare HMAT table with required proximity, latency info.

In Single-Chip scenario, one of the primary use case, of having
extended remote memory area and SRAT,HMAT table, is to avail the
extended remote memory region as CXL.Memory.

Signed-off-by: Sayanta Pattanayak <sayanta.pattanayak@arm.com>
Change-Id: I01488ae9cf34b22177ef3d732f674be3e0409f21