x86 hibernate: Mark ACPI NVS memory region at startup

Introduce new initcall for marking the ACPI NVS memory at startup, so
that it can be saved/restored during hibernation/resume.

Based on a patch by Zhang Rui.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>