power: smb1360: Add logic to reset FG at PON

If the FG is configured for shutdown at power-off
and remains in that state for long, it could impact
the SOC accuracy. To compensate for this, reset the
FG if the predicted voltage at PON is different
than the current voltage by a configurable threshold.

CRs-Fixed: 735604
Change-Id: I68573127bedbc4224a6c57b427f4be8ea5c2fe7e
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>