nvme: fix the nsid value to print in nvme_validate_or_alloc_ns

ns can be NULL at this point, and my move of the check from
the original patch by Chaitanya broke this.

Fixes: 0ec84df4 ("nvme-core: check ctrl css before setting up zns")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/core.c

@@ -4099,7 +4099,7 @@ static void nvme_validate_or_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 		if (!nvme_multi_css(ctrl)) {
 			dev_warn(ctrl->device,
 				"command set not reported for nsid: %d\n",
-				ns->head->ns_id);
+				nsid);
 			break;
 		}
 		nvme_alloc_ns(ctrl, nsid, &ids);