Request incorrect shutdown type when fast reboot

[dawnbeauty]

Description
When fast reboot, we should request syncd FAST shutdown to keep data plane running.

syncd.cpp:

if (shutdownType == SYNCD_RESTART_TYPE_FAST || shutdownType == SYNCD_RESTART_TYPE_WARM)
    {
        SWSS_LOG_NOTICE("Fast/warm reboot requested, keeping data plane running");

        sai_attribute_t attr;

        attr.id = SAI_SWITCH_ATTR_UNINIT_DATA_PLANE_ON_REMOVAL;
        attr.value.booldata = false;

        status = sai_switch_api->set_switch_attribute(gSwitchId, &attr);

        if (status != SAI_STATUS_SUCCESS)
        {
            SWSS_LOG_ERROR("Failed to set SAI_SWITCH_ATTR_UNINIT_DATA_PLANE_ON_REMOVAL=false: %s",
                    sai_serialize_status(status).c_str());
        }
    }

But, in sonic-buildimage/files/scripts/syncd.sh, there are warm and cold shutdown types, seems like it missing the FAST.

    if [[ x"$WARM_BOOT" == x"true" ]]; then
        TYPE=warm
    else
        TYPE=cold
    fi

    if [[ x$sonic_asic_platform == x"mellanox" ]] && [[ x$TYPE == x"cold" ]]; then
        debug "Stopping pmon service ahead of syncd..."
        /bin/systemctl stop pmon
        debug "Stopped pmon service"
    fi

    if [[ x$sonic_asic_platform != x"mellanox" ]] || [[ x$TYPE != x"cold" ]]; then
        debug "${TYPE} shutdown syncd process ..."
        /usr/bin/docker exec -i syncd /usr/bin/syncd_request_shutdown --${TYPE}

Steps to reproduce the issue:

1. fast-reboot

Describe the results you received:
request syncd cold shutdown

Describe the results you expected:
request syncd fast shutdown