tun: Fix xdp_rxq_info's queue_index when detaching

When a queue(tfile) is detached, we only update tfile's queue_index,
but do not update xdp_rxq_info's queue_index. This patch fixes it.

Fixes: 8bf5c4ee

 ("tun: setup xdp_rxq_info")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Link: https://lore.kernel.org/r/1708398727-46308-1-git-send-email-wangyunjian@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>