mtip32xx: blk_mq_init_queue() returns an ERR_PTR

We changed this from blk_alloc_queue_node() to blk_mq_init_queue() so
the check needs to be updated as well.

Fixes: ffc771b3 ('mtip32xx: convert to use blk-mq')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/mtip32xx/mtip32xx.c

@@ -3890,7 +3890,7 @@ static int mtip_block_initialize(struct driver_data *dd)
 
 	/* Allocate the request queue. */
 	dd->queue = blk_mq_init_queue(&dd->tags);
-	if (dd->queue == NULL) {
+	if (IS_ERR(dd->queue)) {
 		dev_err(&dd->pdev->dev,
 			"Unable to allocate request queue\n");
 		rv = -ENOMEM;