Core: create iovec-based veneers for secure functions

Define uniform API for all secure functions to enable
IO buffer sanitization when a secure function call is
made.
If secure function API is adopted for a given secure
function, it no longer needs to add a veneer, which
is instead auto-generated from the manifest file.

Change-Id: If3cdf579b0c39b5c1dff0721b3d563e06582825f
Signed-off-by: Miklos Balint <miklos.balint@arm.com>
11 files changed