Remove link_path from responsive_image theme

Problem/Motivation

In #2123251: Improve DX of responsive images; convert theme functions to new #type element, we missed removing link_path from the following:

/**
 * Implements hook_theme().
 */
function responsive_image_theme() {
  return array(
    'responsive_image' => array(
      'variables' => array(
       <strong> 'link_path' => NULL,</strong>
        'uri' => NULL,
        'attributes' => array(),
        'responsive_image_style_id' => array(),
      ),
    ),
  );
}

We were trying to get this to more closely mimic the similar array for an image and missed removing this. link_path is not used in preprocess or the template so is safe to remove. A rendered responsive_image can be passed into a link on the code level, which is a better approach than link_path.

Proposed resolution

Remove link_path from responsive_image in responsive_image_theme.

Remaining tasks

Commit patch.

User interface changes

None.

API changes

Removes link_path, but link_path doesn't do anything right now and has existed only since #2123251: Improve DX of responsive images; convert theme functions to new #type element was committed.

Beta phase evaluation