drm/omap: tpd12s015: CT_CP_HPD as optional gpio

tpd12s015 HW has LS_OE, CT_CP_HPD and HPD gpios. Out of these gpios,
driver only handled LS_OE as optional. The CT_CP_HPD gpio should also
be treated as optional gpio as it is just a power saving feature. Some
boards hardwire this gpio to be always enable. In this patch, all access
to CT_CP_HPD gpio is made optional.
Signed-off-by: NManisha Agrawal <manisha.agrawal@ti.com>
Acked-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c

@@ -236,7 +236,7 @@ static int tpd_probe(struct platform_device *pdev)
 		return r;
 
 
-	gpio = devm_gpiod_get_index(&pdev->dev, NULL, 0,
+	gpio = devm_gpiod_get_index_optional(&pdev->dev, NULL, 0,
 		 GPIOD_OUT_LOW);
 	if (IS_ERR(gpio))
 		goto err_gpio;