SST: First public draft of PSA SST APIs

This patch releases the first public draft of Platform Security
Architecture (PSA) Secure Storage (SST) APIs.
The APIs are defined in psa_sst_api.h.

More information can be found in tfm_sst_integration_guide.md

The patch also accomodates the SST implementation and tests
accordingly.

Change-Id: Ibe537939f9692a86816fa0c7b2a8d070a502fd2c
Signed-off-by: Marc Moreno <marc.morenoberengue@arm.com>
45 files changed