fbdev: omap2: improve usage of gpiod API

Since 39b2bbe3d715 (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.

Also make use of gpiod_get*_optional where applicable.

Apart from simplification of the affected drivers this is another step
towards making the flags argument to gpiod_get*() mandatory.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c
index eb8fd81..f7be348 100644
--- a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c
+++ b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c
@@ -209,16 +209,9 @@
 	struct videomode vm;
 	struct gpio_desc *gpio;
 
-	gpio = devm_gpiod_get(&pdev->dev, "enable");
-
-	if (IS_ERR(gpio)) {
-		if (PTR_ERR(gpio) != -ENOENT)
-			return PTR_ERR(gpio);
-		else
-			gpio = NULL;
-	} else {
-		gpiod_direction_output(gpio, 0);
-	}
+	gpio = devm_gpiod_get_optional(&pdev->dev, "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
 
 	ddata->enable_gpio = gpio;