Core: thread mode transition for IPC calls

Align NS IPC calls with thread mode NS-S transition
changes

Change-Id: Ifbc4a5229ee0400bde9755d2964bcf82e8fcfca2
Signed-off-by: Miklos Balint <miklos.balint@arm.com>
diff --git a/interface/src/tfm_psa_ns_api.c b/interface/src/tfm_psa_ns_api.c
index 80c3af8..45e8082 100644
--- a/interface/src/tfm_psa_ns_api.c
+++ b/interface/src/tfm_psa_ns_api.c
@@ -35,6 +35,10 @@
                      const psa_outvec *out_vec,
                      size_t out_len)
 {
+    /* FixMe: sanity check can be added to offload some NS thread checks from
+     * TFM secure API
+     */
+
     /* Due to v8M restrictions, TF-M NS API needs to add another layer of
      * serialization in order for NS to pass arguments to S
      */