test: add more tests for Montgomery's invalid masks

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/suites/test_suite_pkparse.function b/tests/suites/test_suite_pkparse.function
index 9361f53..df139c6 100644
--- a/tests/suites/test_suite_pkparse.function
+++ b/tests/suites/test_suite_pkparse.function
@@ -150,8 +150,8 @@
 }
 /* END_CASE */
 
-/* BEGIN_CASE depends_on:MBEDTLS_PK_WRITE_C */
-void pk_parse_fix_x25519(data_t *input_key, data_t *exp_output)
+/* BEGIN_CASE depends_on:MBEDTLS_PK_HAVE_ECC_KEYS:MBEDTLS_PK_WRITE_C */
+void pk_parse_fix_montgomery(data_t *input_key, data_t *exp_output)
 {
     /* Montgomery keys have specific bits set to either 0 or 1 depending on
      * their position. This is enforced during parsing (please see the implementation