RDMA/hns: Use free_pages function instead of free_page

It need to use free_pages function for free the memory allocated
by __get_free_pages function.
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -933,7 +933,7 @@ int hns_roce_ib_umem_write_mtt(struct hns_roce_dev *hr_dev,
 		ret = hns_roce_write_mtt(hr_dev, mtt, n, i, pages);
 
 out:
-	free_page((unsigned long) pages);
+	free_pages((unsigned long) pages, order);
 	return ret;
 }