omapfb: encoder-tpd12s015: fix error return code

Return an error code on failure.

Problem found using Coccinelle.
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/fbdev/omap2/omapfb/displays/encoder-tpd12s015.c

@@ -240,22 +240,28 @@ static int tpd_probe(struct platform_device *pdev)
 
 	gpio = devm_gpiod_get_index_optional(&pdev->dev, NULL, 0,
 		GPIOD_OUT_LOW);
-	if (IS_ERR(gpio))
+	if (IS_ERR(gpio)) {
+		r = PTR_ERR(gpio);
 		goto err_gpio;
+	}
 
 	ddata->ct_cp_hpd_gpio = gpio;
 
 	gpio = devm_gpiod_get_index_optional(&pdev->dev, NULL, 1,
 		GPIOD_OUT_LOW);
-	if (IS_ERR(gpio))
+	if (IS_ERR(gpio)) {
+		r = PTR_ERR(gpio);
 		goto err_gpio;
+	}
 
 	ddata->ls_oe_gpio = gpio;
 
 	gpio = devm_gpiod_get_index(&pdev->dev, NULL, 2,
 		GPIOD_IN);
-	if (IS_ERR(gpio))
+	if (IS_ERR(gpio)) {
+		r = PTR_ERR(gpio);
 		goto err_gpio;
+	}
 
 	ddata->hpd_gpio = gpio;