MAGETWO-64465: Investigate and fix post-refactoring issues

- removed unused code

Author: rganin

app/code/Magento/Catalog/Model/Product/Option/Type/File.php

@@ -6,7 +6,6 @@
 namespace Magento\Catalog\Model\Product\Option\Type;
 
 use Magento\Framework\App\Filesystem\DirectoryList;
-use Magento\Framework\Exception\SerializationException;
 use Magento\Framework\Filesystem;
 use Magento\Framework\Exception\LocalizedException;
 use Magento\Catalog\Model\Product\Exception as ProductException;