make 'preapproved' payments get same access rights as 'complete' payments (issue #1232)

I wrote up a small issue I came across with EDD and EDD Content Restriction in [issue #1232 on the main EDD repo](https://github.com/easydigitaldownloads/Easy-Digital-Downloads/issues/1232).

The little tweak here I've made seems to address this issue and works so far in testing, for me on a local installation at least.