nvme: clear the request_queue pointers on failure in nvme_alloc_io_tag_set

In nvme_alloc_io_tag_set(), the connect_q pointer should be set to NULL
in case of error to avoid potential invalid pointer dereferences.
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -4956,6 +4956,7 @@ int nvme_alloc_io_tag_set(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set,
 
 out_free_tag_set:
 	blk_mq_free_tag_set(set);
+	ctrl->connect_q = NULL;
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nvme_alloc_io_tag_set);