SPM: Remove remaining SMC interfaces

Also, add a disclaimer to explain that the current implementation of SPM
is a prototype that is going to undergo a lot of rework.

Change-Id: I303c1e61c51d9f286cc599fea565fc9ba5a996bf
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
4 files changed