Adjust ssl_tls13_keys.c to consolidated CID/1.3 padding granularity

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 91384f2..902f99e 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -815,7 +815,7 @@
      * type-extended and padded plaintext is therefore the padding
      * granularity. */
     transform->minlen =
-        transform->taglen + MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY;
+        transform->taglen + MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY;
 
     return( 0 );
 }