power: qpnp-fg-gen3: Improve the accuracy of charge_counter

Currently, charge_counter is based off CC_SOC_SW which is based
off coulomb counter. However, there could be some accumulation
of error due to inaccuracy in ADC over time. This can potentially
affect the accuracy of charge_counter. To overcome this, prime
CC_SOC_SW during discharging based off battery SOC and to a full
value during charge termination.

While at it, expose the charge_counter_shadow property based off
battery SOC for comparison.

CRs-Fixed: 2109421
Change-Id: I50de44afbdbd747db95946416a09062df205fd6c
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>