Process State from NOTIFY message.

def notify_callback(self, notify):
        """Process State from NOTIFY message."""
        _LOGGER.debug(notify)
        if notify.ip_address != self.stb_ip:
            return

        if notify.tune:
            self._state = State.PLAYING_LIVE_TV 
            self.tune_src = notify.tune['@src']
            try:
                if notify.stopped:
                    self._state = State.STOPPED
                elif notify.timeshift:
                    self._state = State.PLAYING_TIMESHIFT_TV
                elif notify.recorded:
                    self._state = State.PLAYING_RECORDED_TV
            except PyMediaroomError as e:
                _LOGGER.debug("%s please report at https://github.com/dgomes/pymediaroom/issues", e)
        else:
            self._state = State.STANDBY
        
        _LOGGER.debug("%s is %s", self.stb_ip, self._state)
        return self._state