Input: wacom - properly enable runtime PM

We need to always call usb_autopm_put_interface() in wacom_open(),
not only when initialization fails, otherwise the device will be
marked as PM-busy and will never be put in suspended state.

Based on patch by Oliver Neukum.

Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/tablet/wacom_sys.c

@@ -120,22 +120,25 @@ static int wacom_open(struct input_dev *dev)
 
 out:
 	mutex_unlock(&wacom->lock);
-	if (retval)
-		usb_autopm_put_interface(wacom->intf);
+	usb_autopm_put_interface(wacom->intf);
 	return retval;
 }
 
 static void wacom_close(struct input_dev *dev)
 {
 	struct wacom *wacom = input_get_drvdata(dev);
+	int autopm_error;
+
+	autopm_error = usb_autopm_get_interface(wacom->intf);
 
 	mutex_lock(&wacom->lock);
 	usb_kill_urb(wacom->irq);
 	wacom->open = false;
 	wacom->intf->needs_remote_wakeup = 0;
 	mutex_unlock(&wacom->lock);
 
-	usb_autopm_put_interface(wacom->intf);
+	if (!autopm_error)
+		usb_autopm_put_interface(wacom->intf);
 }
 
 static int wacom_parse_hid(struct usb_interface *intf, struct hid_descriptor *hid_desc,