Merge changes from topic "feat_state_part3" into integration

* changes:
  refactor(cpufeat): enable FEAT_VHE for FEAT_STATE_CHECKED
  refactor(mpam): enable FEAT_MPAM for FEAT_STATE_CHECKED
  feat(libc): add support for fallthrough statement
  refactor(spe): enable FEAT_SPE for FEAT_STATE_CHECKED
  refactor(cpufeat): rename ENABLE_SPE_FOR_LOWER_ELS to ENABLE_SPE_FOR_NS
  fix(spe): drop SPE EL2 context switch code