AppleTV: Make most drivers and inut devices modular

Since most AppleTV users won't have any of these devices (the AppleTV hardware is quite limited in what can be added, and is used in pretty standard outfits) make everything modular that one could have added.

Wrt. non-hardware specific modules (like filesystems or compression modules) I have tested that a kernel with these modules still boots and works fine on standard AppleTV hardware.