Update further type mismatches

Signed-off-by: Ben Taylor <ben.taylor@linaro.org>
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index c2ab27b..000c09a 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -40,7 +40,7 @@
         goto cleanup;
     }
 
-    if (mbedtls_pk_verify_new(csr.sig_pk, &csr.pk,
+    if (mbedtls_pk_verify_ext(csr.sig_pk, &csr.pk,
                               csr.sig_md, hash, mbedtls_md_get_size_from_type(csr.sig_md),
                               csr.sig.p, csr.sig.len) != 0) {
         ret = MBEDTLS_ERR_X509_CERT_VERIFY_FAILED;