Fix -Wundef issues in device config.

The diff is hard to read, but the actual changes are:

* Move the "Device DNS-SD Configuration" section to before the "Thread
  Configuration" section, because "Thread Configuration" uses some of the values
  DNS-SD configuration defines.
* Add explicit defines for CHIP_DEVICE_LAYER_NONE and
  CHIP_DEVICE_CONFIG_ENABLE_NFC (setting them to 0 if not otherwise defined).