USB: add usbfs stubs for suspend and resume

This patch (as1022b) adds stub methods for suspend and resume to the
usbfs driver.  There isn't much they can do since there's no way to
inform a user task about the events.  But it's important to have the
stubs, because an upcoming change to usbcore will automatically unbind
drivers that don't have those methods when a suspend occurs.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/devio.c

@@ -402,10 +402,25 @@ static void driver_disconnect(struct usb_interface *intf)
 	destroy_async_on_interface(ps, ifnum);
 }
 
+/* The following routines are merely placeholders.  There is no way
+ * to inform a user task about suspend or resumes.
+ */
+static int driver_suspend(struct usb_interface *intf, pm_message_t msg)
+{
+	return 0;
+}
+
+static int driver_resume(struct usb_interface *intf)
+{
+	return 0;
+}
+
 struct usb_driver usbfs_driver = {
 	.name =		"usbfs",
 	.probe =	driver_probe,
 	.disconnect =	driver_disconnect,
+	.suspend =	driver_suspend,
+	.resume =	driver_resume,
 };
 
 static int claimintf(struct dev_state *ps, unsigned int ifnum)