Return the major service class property decoded e.g.,
        Audio, Telephony, etc

def major_service_class(self):
        """
        Return the major service class property decoded e.g.,
        Audio, Telephony, etc
        """
        major_service = []
        for i in BTCoD._MAJOR_SERVICE_CLASS.keys():
            if (self.cod & i):
                major_service.append(BTCoD._MAJOR_SERVICE_CLASS[i])
        return major_service