Ah okay.
It's added, but I changed ath to if_ath, that what the driver is named ;)
Now cleaning up previous build and then I'm gonna try this.
Hopefully this time something actually goes as planned.
edit: crap, it checks the name of the folder, not name of the module. So yet another attempt…
edit2: It now shows up as separate module, however, it is also still in the kernel...
(Deleted the driver, Atheros card still recognized and shown in list of interfaces.)