This is as opposed to using ACPI sleep states directly
(ACPI_STATE_S*). We now use POWER_STYPE_* added in D52036.
This is in preparation for adding support for s2idle, which is not an
ACPI sleep state, but needs to be handled specially by
acpi_EnterSleepState.
These are the changes in D52043 + the fixes in D52545 and D52598 already applied.