The CPU nodes should be described as children of "cpus" bus node with
appropriate "reg" properties:

  cpus: '#address-cells' is a required property
  cpus: '#size-cells' is a required property
  cpu: 'device_type' is a required property
  cpu: 'reg' is a required property
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200907183313.29234-11-krzk@kernel.org