tls_mgm: initialize method_max when default is used

This commit does not necessarily fix a bug right now, as the default TLS
method used is SSLv23, therefore the method_max is not even used.
However, if anytime the default will be changed, the max method would
not be set, thus will result in an error.

modules/tls_mgm/tls_mgm.c

@@ -1205,6 +1205,7 @@ static int init_tls_dom(struct tls_domain *d)
 		LM_DBG("no method for tls domain '%.*s', using default\n",
 				d->name.len, ZSW(d->name.s));
 		d->method = tls_default_method;
+		d->method_max = tls_default_method;
 	}
 
 	if (!d->cert.s) {