feat(drtm): add platform API to retrieve ACPI tables region size

Introduces a platform-specific API to retrieve the ACPI table
region size. This will be used in a subsequent patch to specify
the minimum DLME size requirement for the DCE preamble.

Change-Id: I44ce9241733b22fea3cbce9d42f1c2cc5ef20852
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
2 files changed