power: battery: Expose FCC stepper algorithm execution status

Add FCC_STEPPING_IN_PROGRESS property to qcom-battery which exposes
state of FCC stepper algorithm. This allows userspace daemon to skip
any FCC manipulation while FCC stepping is in progress.

Change-Id: If85110fa25bfc49277677848b5a7d3c7d3169ecd
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>