You must install drupal-mode from https://github.com/nyuhuhuu/drupal-mode/blob/master/drupal-mode.el
You may need to create the ~/.emacs.d/plugins/drupal-mode-el/ directory to put the drupal-mode.el file into. And on Debian/Ubuntu you will probably have to install the w3m-el package – but after that you have a Drupal specific php-mode called drupal-mode.
This fixes the issue whereby arrays in php-mode are not indented in the same way that Drupal Coding Standards specify.