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>
diff --git a/test/framework/helpers.h b/test/framework/helpers.h
index 517c4b0..c0e7a7a 100755
--- a/test/framework/helpers.h
+++ b/test/framework/helpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * Copyright (c) 2017-2018, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -29,13 +29,13 @@
 };
 
 /**
- * \brief Translates tfm_sst_err_t into a string.
+ * \brief Translates psa_sst_err_t into a string.
  *
- * \param[in] err  tfm_sst_err_t error value.
+ * \param[in] err  psa_sst_err_t error value.
  *
- * \return tfm_sst_err_t as string.
+ * \return psa_sst_err_t as string.
  */
-const char *sst_err_to_str(enum tfm_sst_err_t err);
+const char *sst_err_to_str(enum psa_sst_err_t err);
 
 /**
  * \brief Translates asset permissions into a string.