Remove API key check in D6 branches

Both the dev and latest beta2 branches still have the following code present. This causes gmap to fail at the first hurdle.

The following was reported by fizk @ http://drupal.org/node/1459606#comment-7229306

<?php
function theme_gmap($element) {
  // Usability: Prevent js errors on first visit to settings page, etc.
  // Of course it will still error if the *wrong* key is on file.
  if (gmap_get_key() == '') {
    //return t('Unable to render map: Google Maps API key is missing.');
  }
?>

And solved with the patch posted by hutch @ http://drupal.org/node/1459606#comment-7252646 but it seemed to have got swallowed up in the large issue so I am reposting.

Patch: http://drupal.org/files/gmap_missing_key_bug-1459606.patch