block/rnbd-clt: fix wrong max ID in ida_alloc_max

We need to pass 'end - 1' to ida_alloc_max after switch from
ida_simple_get to ida_alloc_max.

Otherwise smatch warns.

drivers/block/rnbd/rnbd-clt.c:1460 init_dev() error: Calling ida_alloc_max() with a 'max' argument which is a power of 2. -1 missing?

Fixes: 24afc15 ("block/rnbd: Remove a useless mutex")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20221230010926.32243-1-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Guoqing Jiang

drivers/block/rnbd/rnbd-clt.c

@@ -1440,7 +1440,7 @@ static struct rnbd_clt_dev *init_dev(struct rnbd_clt_session *sess,
 		goto out_alloc;
 	}
 
-	ret = ida_alloc_max(&index_ida, 1 << (MINORBITS - RNBD_PART_BITS),
+	ret = ida_alloc_max(&index_ida, (1 << (MINORBITS - RNBD_PART_BITS)) - 1,
 			    GFP_KERNEL);
 	if (ret < 0) {
 		pr_err("Failed to initialize device '%s' from session %s, allocating idr failed, err: %d\n",