tools: ynl: process unknown for enum values

        pad = b'\x00' * ((4 - len(attr_payload) % 4) % 4)

        return struct.pack('HH', len(attr_payload) + 4, nl_type) + attr_payload + pad

    def _get_enum_or_unknown(self, enum, raw):

        try:

            name = enum.entries_by_val[raw].name

        except KeyError as error:

            if self.process_unknown:

                name = f"Unknown({raw})"

            else:

                raise error

        return name

    def _decode_enum(self, raw, attr_spec):

        enum = self.consts[attr_spec['enum']]

        if enum.type == 'flags' or attr_spec.get('enum-as-flags', False):

            value = set()

            while raw:

                if raw & 1:

                    value.add(enum.entries_by_val[i].name)

                    value.add(self._get_enum_or_unknown(enum, i))

                raw >>= 1

                i += 1

        else:

            value = enum.entries_by_val[raw].name

            value = self._get_enum_or_unknown(enum, raw)

        return value

    def _decode_binary(self, attr, attr_spec):