gpio: use dev_get_platdata()

Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c
index 7216079..5d518d5 100644
--- a/drivers/gpio/gpio-74x164.c
+++ b/drivers/gpio/gpio-74x164.c
@@ -129,7 +129,7 @@
 	if (!chip)
 		return -ENOMEM;
 
-	pdata = spi->dev.platform_data;
+	pdata = dev_get_platdata(&spi->dev);
 	if (pdata && pdata->base)
 		chip->gpio_chip.base = pdata->base;
 	else