platform/x86/intel/pmc: core: Report duration of time in HW sleep state

intel_pmc_core displays a warning when the module parameter
`warn_on_s0ix_failures` is set and a suspend didn't get to a HW sleep
state.

Report this to the standard kernel reporting infrastructure so that
userspace software can query after the suspend cycle is done.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>