ei_touch_button and ei_touch_motion don't work for devices with not exactly one region

	list_for_each(r, &device->regions, link) {
		if (!ei_region_contains(r, x, y)) {
			log_bug_client(ei_device_get_context(device),
				       "%s: touch %u has invalid x/y coordinates", __func__, touch->tracking_id);
			ei_touch_up(touch);
			return;
		}
	}

If the device has no regions, the loop is skipped. If the device has more than one non-overlapping region, the loop will certainly fail.