IB/hns: Fix return value check in hns_roce_get_cfg()

In case of error, the function devm_ioremap_resource() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should
be replaced with IS_ERR().
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_main.c

@@ -715,8 +715,8 @@ static int hns_roce_get_cfg(struct hns_roce_dev *hr_dev)
 
 	res = platform_get_resource(hr_dev->pdev, IORESOURCE_MEM, 0);
 	hr_dev->reg_base = devm_ioremap_resource(dev, res);
-	if (!hr_dev->reg_base)
-		return -ENOMEM;
+	if (IS_ERR(hr_dev->reg_base))
+		return PTR_ERR(hr_dev->reg_base);
 
 	for (i = 0; i < HNS_ROCE_MAX_PORTS; i++) {
 		net_node = of_parse_phandle(np, "eth-handle", i);