gpio: arizona: Remove pointless set of platform drvdata

We use the gpio chip private data in all the callbacks so remove this
redundant line of code.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-arizona.c

@@ -140,8 +140,6 @@ static int arizona_gpio_probe(struct platform_device *pdev)
 		goto err;
 	}
 
-	platform_set_drvdata(pdev, arizona_gpio);
-
 	return ret;
 
 err: