Make ordering work again with stock app search.

After the ProductFullStockView.post_search_callback was changed to use a
subselect, trying to change the order of the list would break the query
(since the column ordered by is not in the subselect).

Just remove the order by part of the query from the subselect.

Change-Id: Ie1bd03c086c7f65a2b1dc122c76a249183b557a1