mtip32xx: fix minor number

When a device is surprise removed and inserted, it is assigned a new minor
number because driver use multiples of 'instance' number. Modified to use the
multiples of 'index' for minor number.
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/mtip32xx/mtip32xx.c

@@ -3857,7 +3857,8 @@ static int mtip_block_initialize(struct driver_data *dd)
 
 	dd->disk->driverfs_dev	= &dd->pdev->dev;
 	dd->disk->major		= dd->major;
-	dd->disk->first_minor	= dd->instance * MTIP_MAX_MINORS;
+	dd->disk->first_minor	= index * MTIP_MAX_MINORS;
+	dd->disk->minors 	= MTIP_MAX_MINORS;
 	dd->disk->fops		= &mtip_block_ops;
 	dd->disk->private_data	= dd;
 	dd->index		= index;