tablet-v2: only send id event is vendor is set

Some tablets may not have a USB vendor/product set.

References: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/issues/180#note_2303637

types/tablet_v2/wlr_tablet_v2_tablet.c

@@ -102,13 +102,14 @@ void add_tablet_client(struct wlr_tablet_seat_client_v2 *seat,
 		client, destroy_tablet_v2);
 	zwp_tablet_seat_v2_send_tablet_added(seat->resource, client->resource);
 
-	// Send the expected events
 	if (tablet->wlr_tablet->base.name) {
 		zwp_tablet_v2_send_name(client->resource,
 			tablet->wlr_tablet->base.name);
 	}
+	if (tablet->wlr_device->vendor != 0) {
 		zwp_tablet_v2_send_id(client->resource,
 			tablet->wlr_device->vendor, tablet->wlr_device->product);
+	}
 
 	const char **path_ptr;
 	wl_array_for_each(path_ptr, &tablet->wlr_tablet->paths) {