Add search to Genesis secondary navigation

/** Changes to child functions.php */
/** Reposition the secondary navigation menu */
remove_action( 'genesis_after_header', 'genesis_do_subnav' );
add_action( 'genesis_before_header', 'genesis_do_subnav' );

/** Add search form to secondary navigation menu */
// Ref link: http://www.billerickson.net/genesis-wordpress-nav-menu-content/
add_filter( 'genesis_nav_items', 'dt_subnav_search', 10, 2 );
add_filter( 'wp_nav_menu_items', 'dt_subnav_search', 10, 2 );
/**
 * @param string $menu
 * @param array $args
 * @return string
 */
function dt_subnav_search ($menu, $args) {
    $args = (array)$args;
    if ( 'secondary' !== $args['theme_location']  )
        return $menu;
    $dtsearch = '<li class="right search">' . genesis_search_form() . '</li>';
    return $menu . $dtsearch;
}

/* Secondary Navigation Extras (copied from Primary Navigation Extras in style sheet) */

#subnav .menu li.right { float: right; font-family: 'Oswald', arial, serif; padding: 10px 15px; }
#subnav .menu li.right a { background: none; border: none; color: #333; display: inline; text-decoration: none; }
#subnav .menu li.right a:hover { color: #ed702b; text-decoration: none; }
#subnav .menu li.search { width: 28%; padding: 7px 10px 0; }
#subnav .menu li.rss a { background: url(images/rss.png) no-repeat center left; margin: 0 0 0 10px; padding: 0 0 0 16px; }
#subnav .menu li.twitter a { background: url(images/twitter-nav.png) no-repeat center left; padding: 0 0 0 20px; }