nvme-core: use nvme_ns_head_multipath instead of ns->head->disk

Change the way we check for a multipath nshead so as
to consistently use the same check to assert the same condition.

Signed-off-by: Irvin Cote <irvincoteg@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Author: i-cote

drivers/nvme/host/core.c

@@ -3664,7 +3664,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 	 * instance as shared namespaces will show up as multiple block
 	 * devices.
 	 */
-	if (ns->head->disk) {
+	if (nvme_ns_head_multipath(ns->head)) {
 		sprintf(disk->disk_name, "nvme%dc%dn%d", ctrl->subsys->instance,
 			ctrl->instance, ns->head->instance);
 		disk->flags |= GENHD_FL_HIDDEN;