platforms/drm: reverse output creation order

This was inverted from 5.22, which switches plasma layouts and the default Xwayland primary screen, which I read a few complaints about (nothing on bugzilla apparently). Not completely 100% sure if this is a good idea as some may have manually re-adjusted their layout to fit already but as we're still at 5.23.0 this can probably prevent the change from reaching the majority of users.