Actually run MD<->PSA test, and fix it

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/tests/suites/test_suite_md.data b/tests/suites/test_suite_md.data
index 0b0afee..9b39e9f 100644
--- a/tests/suites/test_suite_md.data
+++ b/tests/suites/test_suite_md.data
@@ -2,6 +2,9 @@
 MD list
 mbedtls_md_list:
 
+MD <-> PSA conversion
+md_to_from_psa:
+
 MD NULL/uninitialised arguments
 md_null_args: