gpio: mlxbf2: fix return value check in mlxbf2_gpio_get_lock_res()

In case of error, the function devm_ioremap() returns NULL pointer not
ERR_PTR(). The IS_ERR() test in the return value check should be
replaced with NULL test.
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20200427110829.154785-1-weiyongjun1@huawei.comSigned-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mlxbf2.c

@@ -109,8 +109,8 @@ static int mlxbf2_gpio_get_lock_res(struct platform_device *pdev)
 	}
 
 	yu_arm_gpio_lock_param.io = devm_ioremap(dev, res->start, size);
-	if (IS_ERR(yu_arm_gpio_lock_param.io))
-		ret = PTR_ERR(yu_arm_gpio_lock_param.io);
+	if (!yu_arm_gpio_lock_param.io)
+		ret = -ENOMEM;
 
 exit:
 	mutex_unlock(yu_arm_gpio_lock_param.lock);