Sparse reports "warning: incorrect type in return expression (different
address spaces)" because nmk_gpio_populate_chip() is supposed to return
(struct nmk_gpio_chip *) whereas devm_ioremap_resource() returns
(void __iomem *).  ERR_CAST() is needed to fix the warning.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
        res = platform_get_resource(gpio_pdev, IORESOURCE_MEM, 0);
        base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(base))
-               return base;
+               return ERR_CAST(base);
        nmk_chip->addr = base;
 
        clk = clk_get(&gpio_pdev->dev, NULL);