net: rfkill: gpio: make better use of gpiod API

Since 39b2bbe3 (gpio: add flags argument to gpiod_get*() functions)
which appeared in v3.17-rc1, the gpiod_get* functions take an additional
parameter that allows to specify direction and initial value for output.

Furthermore there is devm_gpiod_get_optional which is designed to get
optional gpios.

Simplify driver accordingly.

Note this makes error checking more strict because only -ENOENT is
ignored when searching for the GPIOs which is good.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/rfkill/rfkill-gpio.c

@@ -112,21 +112,17 @@ static int rfkill_gpio_probe(struct platform_device *pdev)
 
 	rfkill->clk = devm_clk_get(&pdev->dev, NULL);
 
-	gpio = devm_gpiod_get(&pdev->dev, "reset");
-	if (!IS_ERR(gpio)) {
-		ret = gpiod_direction_output(gpio, 0);
-		if (ret)
-			return ret;
+	gpio = devm_gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+
 	rfkill->reset_gpio = gpio;
-	}
 
-	gpio = devm_gpiod_get(&pdev->dev, "shutdown");
-	if (!IS_ERR(gpio)) {
-		ret = gpiod_direction_output(gpio, 0);
-		if (ret)
-			return ret;
+	gpio = devm_gpiod_get_optional(&pdev->dev, "shutdown", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+
 	rfkill->shutdown_gpio = gpio;
-	}
 
 	/* Make sure at-least one of the GPIO is defined and that
 	 * a name is specified for this instance