power: battery: Expose FCC stepper work execution status

Add FCC_STEPPER_STATUS property to qcom-battery class to expose
fcc stepper work execution status for thermal balancer user space
daemon.

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