drm/panel: nt39016: Make use of the helper function dev_err_probe()

When possible use dev_err_probe help to properly deal with the
PROBE_DEFER error, the benefit is that DEFER issue will be logged
in the devices_deferred debugfs file.
And using dev_err_probe() can reduce code size, the error value
gets printed.
Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210916104620.11569-1-caihuoqing@baidu.com

drivers/gpu/drm/panel/panel-novatek-nt39016.c

@@ -258,16 +258,13 @@ static int nt39016_probe(struct spi_device *spi)
 		return -EINVAL;
 
 	panel->supply = devm_regulator_get(dev, "power");
-	if (IS_ERR(panel->supply)) {
-		dev_err(dev, "Failed to get power supply\n");
-		return PTR_ERR(panel->supply);
-	}
+	if (IS_ERR(panel->supply))
+		return dev_err_probe(dev, PTR_ERR(panel->supply),
+				     "Failed to get power supply\n");
 
 	panel->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
-	if (IS_ERR(panel->reset_gpio)) {
-		dev_err(dev, "Failed to get reset GPIO\n");
-		return PTR_ERR(panel->reset_gpio);
-	}
+	if (IS_ERR(panel->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(panel->reset_gpio), "Failed to get reset GPIO\n");
 
 	spi->bits_per_word = 8;
 	spi->mode = SPI_MODE_3 | SPI_3WIRE;
@@ -287,11 +284,8 @@ static int nt39016_probe(struct spi_device *spi)
 		       DRM_MODE_CONNECTOR_DPI);
 
 	err = drm_panel_of_backlight(&panel->drm_panel);
-	if (err) {
-		if (err != -EPROBE_DEFER)
-			dev_err(dev, "Failed to get backlight handle\n");
-		return err;
-	}
+	if (err)
+		return dev_err_probe(dev, err, "Failed to get backlight handle\n");
 
 	drm_panel_add(&panel->drm_panel);