Access one field from another when using entities
You mentioned you are using ECK to create a new entity, whereas in your code, you are using 'node' instead of the machine name of your entity.

I am referring to the line:

$field_image_positon = field_get_items('node', $variables['element']['#object'], 'field_image_position');


Change node in this line to your_entity_machine_name.