Add access control for comment setting to UI.

On our site I only want specific support roles to be able to receive new comments and don't want to rely on the users selecting disable.

The way we are solving this is to make it an access control such as:

change notify_perm

function notify_perm() {
  return array('access notify', 'send comments', 'administer notify');
}

in function notify_user_settings_form

    if (user_access('send comments')){
      $form['notify_page_detailed']['comment'] = array('#type' => 'radios',
        '#title' => t('Notify new comments'),
        '#default_value' => $notify->comment,
        '#options' => array(t('Disabled'), t('Enabled')),
        '#description' => t('Include new comments in the notification mail.'),
      );
    };

this way only the users I want to be able to choose if they receive the new comments or not can change it to enabled.