power: battery: Change FCC stepper period to 100ms for PM8150B

FCC stepper algorihtm, when enabled, gradually ramps up/down the limit
whenever there is a FCC change. The default step rate is 100mA/sec.

This change provides a generic way to customize both step size and
period based on PMIC. In addition, set FCC step period to 100 ms for
PM8150B as per the hardware recommendation.

Change-Id: Iec8f952c3afb5050549289dcb3330f40062b3e85
Signed-off-by: Harry Yang <harryy@codeaurora.org>