Add high frequency impedance notification support under DPTF.
This returns high frequency impedance value that can be obtained
from battery fuel gauge whenever there is change over a threshold.
Also, corrected the typo from IMPEDANCED_CHNGED to IMPEDANCE_CHANGED.
Signed-off-by: Sumeet Pawnikar <sumeet.r.pawnikar@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>