rnbd-clt: adjust the layout of struct rnbd_clt_dev

While at it, let re-arrange the struct to remove holes.

Before, pahole reports

	/* size: 232, cachelines: 4, members: 17 */
	/* sum members: 224, holes: 2, sum holes: 8 */
	/* last cacheline: 40 bytes */

After the change, the report changes to

	/* size: 224, cachelines: 4, members: 17 */
	/* last cacheline: 32 bytes */

Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20220706133152.12058-6-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/rnbd/rnbd-clt.h

@@ -106,6 +106,7 @@ struct rnbd_queue {
 };
 
 struct rnbd_clt_dev {
+	struct kobject		kobj;
 	struct rnbd_clt_session	*sess;
 	struct request_queue	*queue;
 	struct rnbd_queue	*hw_queues;
@@ -114,15 +115,14 @@ struct rnbd_clt_dev {
 	u32			clt_device_id;
 	struct mutex		lock;
 	enum rnbd_clt_dev_state	dev_state;
+	refcount_t		refcount;
 	char			*pathname;
 	enum rnbd_access_mode	access_mode;
 	u32			nr_poll_queues;
 	u64			size;		/* device size in bytes */
 	struct list_head        list;
 	struct gendisk		*gd;
-	struct kobject		kobj;
 	char			*blk_symlink_name;
-	refcount_t		refcount;
 	struct work_struct	unmap_on_rmmod_work;
 };