Fix style issues in mac_sign_verify_multi()

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index e7df346..dfde761 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -2721,21 +2721,21 @@
         /* Split data into length(data_part_len) parts. */
         mbedtls_test_set_step( 2000 + data_part_len );
 
-        if( !mac_multipart_internal_func( key_type_arg, key_data,
-                                           alg_arg,
-                                           input, data_part_len,
-                                           expected_mac,
-                                           is_verify, 0 ) )
+        if( mac_multipart_internal_func( key_type_arg, key_data,
+                                         alg_arg,
+                                         input, data_part_len,
+                                         expected_mac,
+                                         is_verify, 0 ) == 0 )
             break;
 
         /* length(0) part, length(data_part_len) part, length(0) part... */
         mbedtls_test_set_step( 3000 + data_part_len );
 
-        if( !mac_multipart_internal_func( key_type_arg, key_data,
-                                           alg_arg,
-                                           input, data_part_len,
-                                           expected_mac,
-                                           is_verify, 1 ) )
+        if( mac_multipart_internal_func( key_type_arg, key_data,
+                                         alg_arg,
+                                         input, data_part_len,
+                                         expected_mac,
+                                         is_verify, 1 ) == 0 )
             break;
     }