Add separate test for mbedtls_mpi_free() accepting NULL
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index ff25a6f..8b5f97d 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -1,4 +1,7 @@
-Parameter validation
+MPI - Valid parameters
+mpi_valid_param:
+
+MPI - Invalid parameters
 mpi_invalid_param:
 
 Arguments with no value