gpio: timberdale: Improve a size determination

Replace the specification of a data structure by a pointer dereference
as the parameter for the operator "sizeof" to make the corresponding size
determination a bit safer according to the Linux coding style convention.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-timberdale.c

@@ -238,7 +238,7 @@ static int timbgpio_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	tgpio = devm_kzalloc(dev, sizeof(struct timbgpio), GFP_KERNEL);
+	tgpio = devm_kzalloc(dev, sizeof(*tgpio), GFP_KERNEL);
 	if (!tgpio)
 		return -EINVAL;