power: pm8921-bms: Update the FCC learning algorithm

1. Add configurable parameters to
	- enable/disable fcc learning
	- minimum soc to start FCC learning
	- minimum ocv (pc) to start FCC learning
	- minimum cycles to update fcc vs temp. table

2. New FCC is calculated using the cc count-
	FCC_NEW = (cc_end - cc_start) / (soc2 - soc1)
	cc_end = CC count when charing ends
	cc_start = CC count when charging starts
	soc1, soc2 = starting and ending SOC_rbatt value

3. Add a new sysfs entries to update the learnt fcc values
   to userspace. These values are restored back on
   reboot.

CRs-Fixed: 417288
Change-Id: I0dc713d59ef9c45f96b9f0b5844252758bd09320
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>
Signed-off-by: Sridhar Gujje <sgujje@codeaurora.org>