image_admin_settings_validate() was inspecting $form[...]['#value'] inappropriately

as per http://drupal.org/node/231622#comment-3130422

> + * CHANGELOG - this was using $form[...]['#value'] where it should have been
+ * using $form_state['values']. Changed it to behave normally, but unsure if the
+ * previous method was intentional. - dman

I've a feeling that's D5 code that never got updated. Could someone file an issue with this and check in old FormAPI docs if that's the case? We should fix this as a separate patch.

Here's the patch that JUST fixes the validate to use $form_state['values'].

I tested a little, behavior is the same as before, only the code style is more correct.

Branched off into its own issue on request, because this trivial left-over code style fix-up is stalling the big feature which wanted to fix it. #231622: Use imagecache as a process for normal image.module presets

Lets see if I've got the right flags for testbot this time araound...