get_custom_logoの内容を変更

function hogehoge_get_custom_logo() {
    $custom_logo_id = get_theme_mod( 'custom_logo' );
    $html = sprintf( '%2$s',
        esc_url( home_url( '/' ) ),
        wp_get_attachment_image( $custom_logo_id, 'full', false, array(
            'class'    => 'custom-logo',
        ) )
    );
    return $html;
}
add_filter( 'get_custom_logo', 'hogehoge_get_custom_logo' );