drm/tilcdc: use devm_of_find_backlight

Look up backlight device using devm_of_find_backlight().
This simplifies the code and prevents us from hardcoding
the node name in the driver.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200514191001.457441-3-sam@ravnborg.org

drivers/gpu/drm/tilcdc/tilcdc_panel.c

@@ -299,7 +299,8 @@ static struct tilcdc_panel_info *of_get_panel_info(struct device_node *np)
 
 static int panel_probe(struct platform_device *pdev)
 {
-	struct device_node *bl_node, *node = pdev->dev.of_node;
+	struct device_node *node = pdev->dev.of_node;
+	struct backlight_device *backlight;
 	struct panel_module *panel_mod;
 	struct tilcdc_module *mod;
 	struct pinctrl *pinctrl;
@@ -315,16 +316,10 @@ static int panel_probe(struct platform_device *pdev)
 	if (!panel_mod)
 		return -ENOMEM;
 
-	bl_node = of_parse_phandle(node, "backlight", 0);
-	if (bl_node) {
-		panel_mod->backlight = of_find_backlight_by_node(bl_node);
-		of_node_put(bl_node);
-
-		if (!panel_mod->backlight)
-			return -EPROBE_DEFER;
-
-		dev_info(&pdev->dev, "found backlight\n");
-	}
+	backlight = devm_of_find_backlight(&pdev->dev);
+	if (IS_ERR(backlight))
+		return PTR_ERR(backlight);
+	panel_mod->backlight = backlight;
 
 	panel_mod->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
 							 GPIOD_OUT_LOW);