Move back timing.c to mbedtls

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/scripts/config.py b/scripts/config.py
index 69ee3ef..df9fc33 100755
--- a/scripts/config.py
+++ b/scripts/config.py
@@ -220,6 +220,7 @@
             'MBEDTLS_DEBUG_C', # part of libmbedtls
             'MBEDTLS_NET_C', # part of libmbedtls
             'MBEDTLS_PKCS7_C', # part of libmbedx509
+            'MBEDTLS_TIMING_C', # part of libmbedtls
             'MBEDTLS_ERROR_C', # part of libmbedx509
             'MBEDTLS_ERROR_STRERROR_DUMMY', # part of libmbedx509
     ]: