Add support for dynamic SST configuration change

- Implement the CurrentOperatingConfig getters to dynamically read
  configuration via PECI. The approach is to read the value from
  PECI for each D-Bus read. When the host is off, return "default"
  values, and when the host is on but the read fails, return the last
  read (cached) values.
- Implement the CurrentOperatingConfig setters to modify configuration
  via PECI.

Tested:
- Change SST-PP profile and SST-BF flag via D-Bus properties, and
  confirmed that host-side Linux tool shows changes.
- Change while host off and confirm it's rejected.
- Change while host booting and confirm it's rejected.
- Read configuration while host off and confirm last known values are
  returned.
- Read configuration while host booting and confirm actual values are
  returned.
- Change on ICX after host booted and confirm it's rejected.

Signed-off-by: Jonathan Doman <jonathan.doman@intel.com>
Change-Id: Ie6eed8ab23bff289e01d6d125402a5509d3a9110
3 files changed