feat(lfa): add initial implementation for LFA_ACTIVATE

This patch introduces the overall handling of the LFA_ACTIVATE call,
including input validation and invocation flow.
While this covers the core implementation, per-component-specific
handling will be developed in a separate patch. The respective
component callbacks are invoked as part of this logic.

Change-Id: Ie9d4584fc0c0abc9a9faffed62165b4461efed3a
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
3 files changed