Fix layer assingment logic

I'm not sure if I understood your two layers correctly, but they didn't make much sense to me. Here's what I thought they should be:
* Layer 1 has the portals where a resonator upgrade can achieve a portal levelup
* Layer 2 has all the other portals that are upgradeable, but do not yield an increase in portal level.

That's the behaviour this change introduces, anyway. I hope I understood you correctly ;)