nvme-loop: check for NVME_LOOP_Q_LIVE in nvme_loop_destroy_admin_queue()

We need to check the NVME_LOOP_Q_LIVE flag in
nvme_loop_destroy_admin_queue() to protect against duplicate
invocations eg during concurrent reset and remove calls.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>