Merge changes from topic "bk/pabandon_cleanup" into integration

* changes:
  feat(cpus): add pabandon support to the Alto cpu
  feat(psci): optimise clock init on a pabandon
  feat(psci): check that CPUs handled a pabandon
  feat(psci): make pabandon support generic
  refactor(psci): unify coherency exit between AArch64 and AArch32
  refactor(psci): absorb psci_power_down_wfi() into common code
  refactor(platforms): remove usage of psci_power_down_wfi
  fix(cm): disable SPE/TRBE correctly