SST: Use get caller client ID API in SST

This change modifies SST service to use
tfm_core_get_caller_client_id(...), provided by the TF-M core, instead
of use the client ID provided by the dummy ID manager via the SST APIs.

The details of this change are:
 - Remove client_id from the veneer API of SST (except for the read
   operation, as referenced read is still possible)
 - Remove the dummy ID manager
 - Add documentation on how to integrate this new method to a NS
   application
 - Change Asset management to work with non-hardcoded secure
   client ID

Change-Id: Ic97ea7aa5840d7e212adc009fa39c1c505440965
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
diff --git a/interface/include/tfm_api.h b/interface/include/tfm_api.h
index c450c7c..efe24e9 100644
--- a/interface/include/tfm_api.h
+++ b/interface/include/tfm_api.h
@@ -14,6 +14,26 @@
 
 #include <stdint.h>
 
+#define TFM_INVALID_CLIENT_ID 0
+
+/**
+ * \brief Checks if the provided client ID is a secure client ID.
+ *
+ * \param[in] client_id Client ID to check
+ *
+ * \return Returns 1 if the client Id is secure. Otherwise, returns 0.
+ */
+#define TFM_CLIENT_ID_IS_S(client_id)  ((client_id)>0)
+
+/**
+ * \brief Checks if the provided client ID is a non-secure client ID.
+ *
+ * \param[in] client_id Client ID to check
+ *
+ * \return Returns 1 if the client Id is non-secure. Otherwise, returns 0.
+ */
+#define TFM_CLIENT_ID_IS_NS(client_id) ((client_id)<0)
+
 /* FixMe: sort out DEBUG compile option and limit return value options
  * on external interfaces */
 /* Note: