fix: Remove calls to '_power_all' method (#493)
fix: Remove calls to '_power_all' method (#493)

Commit 68db71d replaced the 'ValidateClusterHardware' '_power_all'
method with 'set_power_clients' and 'set_bootdev_clients'.
open-power-ref-design-toolkit/cluster-genesis,open-power-ref-design-toolkit/cluster-genesis