feat(smcc): introduce a new vendor_el3 service for ACS SMC handler

In preparation to add support for the Architecture Compliance Suite
SMC services, reserve a SMC ID and introduce a handler function.
Currently, an empty placeholder function is added and future support
will be introduced for the handler support.

More info on System ACS, please refer below link,
https://developer.arm.com/Architectures/Architectural%20Compliance%20Suite

Signed-off-by: Nandan J <Nandan.J@arm.com>
Change-Id: Ib13ccae9d3829e3dcd1cd33c4a7f27efe1436d03
7 files changed