remove ifndef guard

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/tests/configs/tls13-only.h b/tests/configs/tls13-only.h
index faba232..0a22c54 100644
--- a/tests/configs/tls13-only.h
+++ b/tests/configs/tls13-only.h
@@ -22,18 +22,12 @@
  *  limitations under the License.
  */
 
+#define MBEDTLS_SSL_PROTO_TLS1_3
+#define MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
+
 #undef MBEDTLS_SSL_ENCRYPT_THEN_MAC
 #undef MBEDTLS_SSL_EXTENDED_MASTER_SECRET
 #undef MBEDTLS_SSL_PROTO_TLS1_2
-
-#if !defined(MBEDTLS_SSL_PROTO_TLS1_3)
-#define MBEDTLS_SSL_PROTO_TLS1_3
-#endif
-
-#if !defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
-#define MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
-#endif
-
 #undef MBEDTLS_SSL_PROTO_DTLS
 #undef MBEDTLS_SSL_DTLS_ANTI_REPLAY
 #undef MBEDTLS_SSL_DTLS_HELLO_VERIFY