sst: Rediscover profiles after host reboot

In some cases, host processor reboot may change the static SST-PP
profile information. This commit adds ability to register callbacks to
run upon hostState changes, and reruns SST discovery whenever the host
exits the power-off state.

Tested:
- Ran tools/sst-compare-redfish-os.py tool on platform with SPR host
  CPU, and observed no mismatches before and after a host reboot.
- Confirmed Redfish OperatingConfig properties still populated when host
  is off.

Signed-off-by: Jonathan Doman <jonathan.doman@intel.com>
Change-Id: I9e7b0ebb8c5ec7a8464346f3476490b765579428
5 files changed