power: battery: fix FCC stepper calculation

Fix parallel charger's target FCC calculation in
the FCC stepper logic.
Also, add logic to start FCC stepper from MIN_ILIM this
will ensure CP gets enabled at the start of stepper algorithm
and userspace daemon can continue it's optimization.

Change-Id: Ie6797c03872e65a048466bd3d5edaa09cfef728f
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>