WordPress: remove inline width from figure

gistfile1.php

<?php
	add_shortcode('wp_caption', 'fixed_img_caption_shortcode');
    add_shortcode('caption', 'fixed_img_caption_shortcode');
    function fixed_img_caption_shortcode($attr, $content = null) {
        if ( ! isset( $attr['caption'] ) ) {
            if ( preg_match( '#((?:<a [^>]+>\s*)?<img [^>]+>(?:\s*</a>)?)(.*)#is', $content, $matches ) ) {
                $content = $matches[1];
                $attr['caption'] = trim( $matches[2] );
            }
        }
        $output = apply_filters('img_caption_shortcode', '', $attr, $content);
        if ( $output != '' )
            return $output;
        extract(shortcode_atts(array(
            'id'      => '',
            'align'   => 'alignnone',
            'width'   => '',
            'caption' => ''
        ), $attr));
        if ( 1 > (int) $width || empty($caption) )
            return $content;
        if ( $id ) $id = 'id="' . esc_attr($id) . '" ';
        return '<figure ' . $id . ' ' . esc_attr($align) . '" style="width: auto">'
        . do_shortcode( $content ) . '<figcaption class="-text">' . $caption . '</figcaption></figure>'; 
    }
?>