usb: cdc-wdm: manage_power should always set needs_remote_wakeup

Cc: stable <stable@vger.kernel.org>
Reported-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>