Remove additional calls to mbedtls_pk_verify_ext

Signed-off-by: Ben Taylor <ben.taylor@linaro.org>
diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index f5cdc65..372bf84 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -306,7 +306,7 @@
                                      p, signature_len)) == 0) {
         return 0;
     }
-    MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_pk_verify_ext", ret);
+    MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_pk_verify_new", ret);
 
 error:
     /* RFC 8446 section 4.4.3