power: qpnp-fg: add support for ESR pulse tuning feature

Currently, ESR is being under-estimated when the battery state of
charge (SOC) is less than 2%. Add a change which can do tuning to
use default ESR values when SOC is less than 2% and switch back
to ESR extraction when SOC goes above 2%. When the SOC is greater
than 2% and less than 5%, apply slow settings for ESR pulse. When
the SOC crosses 5%, apply the default settings.

This will allow the SOC to increase more accurately when the FG
starts with a better ESR value. This feature is supported via
device tree property "qcom,esr-pulse-tuning-en".

CRs-Fixed: 953448
Change-Id: I37da8d2a9d795dc3d4daffeaf80a72d188243bfd
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>