coreos-kernel: enable ILO and assorted PHY drivers

- Support configuring HP iLO, user space should use a container.
- Many ethernet drivers also need a PHY driver but the associated PHY
  drivers are not enabled automatically. This change enables all the
  ones that appear to be related to ethernet drivers we already ship.

Fixes https://github.com/coreos/coreos-overlay/issues/975 and https://github.com/coreos/bugs/issues/196