driver core/platform_device_add_data: set platform_data to NULL if !data

This makes the data = NULL case more consistent to the data != NULL case.
The functional change is that now

	platform_device_add_data(somepdev, NULL, somesize)

sets pdev->dev.platform_data to NULL instead of not touching it.
Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/platform.c

@@ -220,17 +220,16 @@ EXPORT_SYMBOL_GPL(platform_device_add_resources);
 int platform_device_add_data(struct platform_device *pdev, const void *data,
 			     size_t size)
 {
-	void *d;
+	void *d = NULL;
 
-	if (!data)
-		return 0;
-
-	d = kmemdup(data, size, GFP_KERNEL);
-	if (d) {
-		pdev->dev.platform_data = d;
-		return 0;
+	if (data) {
+		d = kmemdup(data, size, GFP_KERNEL);
+		if (!d)
+			return -ENOMEM;
 	}
-	return -ENOMEM;
+
+	pdev->dev.platform_data = d;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(platform_device_add_data);