power: qpnp-fg-gen4: Add support for configuring more Ki coefficients

Currently, GEN4 FG driver supports configuring Ki coefficients
for medium and high discharging conditions based on the SOC
thresholds. In addition, add support to configure Ki coefficients
for low discharging conditions based on SOC thresholds. Also, add
support to configure Ki coefficients for low, medium and high
charging conditions one time during HW initialization based on
the device tree property.

Change-Id: I8e72bb19f594ac072b4df37d1433b8676c85e5b4
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>