freedreno/rnn: Return success when parsing addvariant

This was missed when I initially added addvariant.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6070>

src/freedreno/rnn/rnn.c

@@ -203,6 +203,7 @@ static int trytypeattr (struct rnndb *db, char *file, xmlNode *node, xmlAttr *at
 		return 1;
 	} else if (!strcmp(attr->name, "addvariant")) {
 		ti->addvariant = getboolattrib(db, file, node->line, attr);
+		return 1;
 	}
 	return 0;
 }