feat(tsp): add ffa_helpers to enable more FF-A functionality

Include ffa_helpers originally taken from the TF-A Tests repo
to provide support for additional FF-A functionality.

Change-Id: Iacc3ee270d5e3903f86f8078ed915d1e791c1298
Signed-off-by: Marc Bonnici <marc.bonnici@arm.com>
Signed-off-by: Shruti Gupta <shruti.gupta@arm.com>
3 files changed