doc: security/etsi: Provision 5.1.5 assessment

Add self-assessment for provision 5.1.5

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
diff --git a/doc/security/standards/etsi-303645.rst b/doc/security/standards/etsi-303645.rst
index 55162e2..f41b34b 100644
--- a/doc/security/standards/etsi-303645.rst
+++ b/doc/security/standards/etsi-303645.rst
@@ -230,8 +230,8 @@
         authentication mechanisms via network interfaces
         impracticable.
       - M C
-      -
-      -
+      - N
+      - **TODO**
 
         .. _ETSI_Provision_5_2_1:
     * - Provision 5.2-1