power: step-chg-jeita: Add support to tune hysteresis for jeita-fcc-step

Allow configuring the rising and falling hysteresis to allow better fine
tuning of the charge current across battery temperature thresholds.

Change-Id: I88419d0694f0e70a6f1115e144685381e29cfd96
Signed-off-by: Ashish Chavan <ashichav@codeaurora.org>