<?php
$comments = get_comments( array(
    'post_status' => 'publish',
    'meta_query'  => array(
        'relation' => 'OR',
        array(
            'key'     => 'cld_like_count',
            'compare' => 'EXISTS',
        ),
        array(
            'key'     => 'cld_like_count',
            'compare' => 'NOT EXISTS',
        ),
    ),
    'orderby'     => 'meta_value_num',
    'order'       => 'DESC',
) );

// Temporarily disable threaded (nested) comments.
add_filter( 'option_thread_comments', '__return_false' );

wp_list_comments( array(
    'callback' => 'listingo_comments',
), $comments );

// Now remove the above filter.
remove_filter( 'option_thread_comments', '__return_false' );