Add catagory attribute to custom shortcode

Question

I have created a custom post type called "whiz_qt_quote". I have created a shortcode for display all the post . This is working fine. but I would like to display the post for specific category. I need a code which would be something like [quote category="motivation"] and it would only display the posts from the "motivation" category.

I am using the following code for the shortcode at the moment. I just need to add the category attribute somehow:

if (!defined('ABSPATH')) exit;

function whiz_qt_feed_shortcode( $atts ) {
    extract( shortcode_atts( array( 'limit' => 3, 'type' => 'whiz_qt_quote','category' => ''), $atts ) );
    global $paged;
    $paged = get_query_var('paged') ? get_query_var('paged') : 1;  

        $args = query_posts(  array ( 
        'posts_per_page' => $limit, 
        'post_type' => $type, 
        'order' => 'ASC', 
        // 'orderby' =>'menu_order', 
        'paged' => $paged ,
        'category_name' => $category) );
        if ( ! empty( $category ) ) {
        $args['category_name'] = $category;
    }
$list = ' ';   
while ( have_posts() ) { the_post();

    $list .= '<article class="listing-view clearfix">' 
    . '<div class="listing-content">' 
    . '<h3><a href="' . get_permalink() . '">' . get_the_title() . '</a></h3>' 
    .'<p>' . get_the_excerpt() . '</p>'
    . '</div>'
    . '</article>';
}

return 
'<div class="listings clearfix">' 
. $list 
. '<div class="nav-previous">' . get_next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts' ) ) . '</div>'
. '<div class="nav-next">' . get_previous_posts_link( __( 'Newer posts <span class="meta-nav">&rarr;</span>' ) ) . '</div>'
. '</div>' .
wp_reset_query();

}
add_shortcode( 'quote', 'whiz_qt_feed_shortcode' );
?>`