SPMD: add support for an example SPM core manifest

This patch repurposes the TOS FW configuration file as the manifest for
the SPM core component which will reside at the secure EL adjacent to
EL3. The SPM dispatcher component will use the manifest to determine how
the core component must be initialised. Routines and data structure to
parse the manifest have also been added.

Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Signed-off-by: Artsem Artsemenka <artsem.artsemenka@arm.com>
Change-Id: Id94f8ece43b4e05609f0a1d364708a912f6203cb