function addParent($array, $parent = null) {
  $result = [];
  foreach ($array as $key => $value) {
    if (is_null($parent)) {
      $result[] = $value['@attributes'];
      $result = array_merge($result, addParent($value['category'], $value['@attributes']['code']));
    } else {
      $result[] = array_merge($value['@attributes'], ['code_parent' => $parent]);
    }
  }
  return $result;
}

$result = addParent($getSection);
print_r($result);