null_blk: Remove usage of the deprecated ida_simple_xx() API

ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove().

This is less verbose.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/bf257b1078475a415cdc3344c6a750842946e367.1705222845.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: tititiou36

drivers/block/null_blk/main.c

@@ -1840,7 +1840,7 @@ static void null_del_dev(struct nullb *nullb)
 
 	dev = nullb->dev;
 
-	ida_simple_remove(&nullb_indexes, nullb->index);
+	ida_free(&nullb_indexes, nullb->index);
 
 	list_del_init(&nullb->list);
 
@@ -2174,7 +2174,7 @@ static int null_add_dev(struct nullb_device *dev)
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
 
 	mutex_lock(&lock);
-	rv = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
+	rv = ida_alloc(&nullb_indexes, GFP_KERNEL);
 	if (rv < 0) {
 		mutex_unlock(&lock);
 		goto out_cleanup_zone;