power: battery/smb-lib: read FCC stepper parameters via device tree

Add support to read the below FCC-stepper configurations:
step-size  - Defines the FCC stepper's step-size.
step-delay - Defines the rate of change of each FCC step.

While at it, pass all the necessary charger parameters to the common
battery.c.

Change-Id: Ic302609daefe37fc2dd16e7b768a5d4dd8a7bd7f
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>