With the standard template defaults there is no way to do this, so you will have to edit the code directly 
In /includes/templates/YOURTEMPLATE/templates there should be a file called tpl_product_info_display.php. If it is not there copy the file from /includes/templates/template_default/templates into that directory, that will mean you can undo this without any hassle.
Now hackety, hack hack hack change the code around line 25 which says
PHP Code:
<!--bof Category Icon -->
<?php if ($module_show_categories != 0) {?>
<?php
/**
* display the category icons
*/
require($template->get_template_dir('/tpl_modules_category_icon_display.php',DIR_WS_TEMPLATE, $current_page_base,'templates'). '/tpl_modules_category_icon_display.php'); ?>
<?php } ?>
<!--eof Category Icon -->
to
PHP Code:
<!--bof Category Icon -->
<?php if ($module_show_categories != 0) {?>
<?php
/**
* display the category icons
*/
define( "SWITCH_CATEGORY_FOR_MANUFACTURER", true );
if( (int)$product_info->fields["manufacturers_id"] != 0 ) {
$manufacturerLink = '<a href="' . zen_href_link( FILENAME_DEFAULT, 'manufacturers_id=' . $product_info->fields["manufacturers_id"] ) . '">' . TEXT_PRODUCT_MANUFACTURER . $manufacturers_name . '</a>';
} else {
$manufacturerLink = TEXT_PRODUCT_MANUFACTURER . "No manufacturer specified";
}
if( SWITCH_CATEGORY_FOR_MANUFACTURER ){?>
<div align="<?php echo $align; ?>" id="manufacturerName" class="manufacturerName"><?php echo $manufacturerLink; ?></div>
<?php
} else {
require($template->get_template_dir('/tpl_modules_category_icon_display.php',DIR_WS_TEMPLATE, $current_page_base, 'templates'). '/tpl_modules_category_icon_display.php');
}}
?>
<!--eof Category Icon -->
Setting true to false in the code above reverts to default behaviour.