w1-gpio: handle of_get_gpio() returning -EPROBE_DEFER better

of_get_gpio() might return -EPROBE_DEFER meaning that the driver
providing the gpio isn't ready yet. If that happens for the first gpio
the resulting kernel output without this patch is:

	w1-gpio somename: Failed to parse DT
	platform somename: Driver w1-gpio requests probe deferral

The first message is misleading and so is suppressed with this patch.

Further if determining the gpio to switch the external pullup yields
-EPROBE_DEFER this error should be passed back to the caller instead of
just continuing without pullup.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/w1/masters/w1-gpio.c

@@ -89,11 +89,22 @@ static int w1_gpio_probe_dt(struct platform_device *pdev)
 		pdata->is_open_drain = 1;
 
 	gpio = of_get_gpio(np, 0);
-	if (gpio < 0)
+	if (gpio < 0) {
+		if (gpio != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+					"Failed to parse gpio property for data pin (%d)\n",
+					gpio);
+
 		return gpio;
+	}
 	pdata->pin = gpio;
 
-	pdata->ext_pullup_enable_pin = of_get_gpio(np, 1);
+	gpio = of_get_gpio(np, 1);
+	if (gpio == -EPROBE_DEFER)
+		return gpio;
+	/* ignore other errors as the pullup gpio is optional */
+	pdata->ext_pullup_enable_pin = gpio;
+
 	pdev->dev.platform_data = pdata;
 
 	return 0;
@@ -107,10 +118,8 @@ static int w1_gpio_probe(struct platform_device *pdev)
 
 	if (of_have_populated_dt()) {
 		err = w1_gpio_probe_dt(pdev);
-		if (err < 0) {
-			dev_err(&pdev->dev, "Failed to parse DT\n");
+		if (err < 0)
 			return err;
-		}
 	}
 
 	pdata = dev_get_platdata(&pdev->dev);