power: qpnp-bms: introduce configurable corrections

There are situations when the corrections can cause linearity issues.
Provide a scheme to limit the corrections via a configurable parameters.
The corrections were introduced to prevent battery dipping below UVLO.
If the battery were in the flat portion of the SOC curve a small error
in OCV measurement could drift the SOC by a large amount. Corrections
are important if the OCV falls in this range. Hence introduce two
parameters to limit the corrections based on a OCV threshold - one when
it is above 3.8 volts, where corrections could be low and the other
when the OCV is lower and 3.8 (flat portion) where corrections should be
high.

Also there are instances when the SOC appears stuck at 1% for a long
time. This is because the algorithm doesn't allow the soc to drop to 0%
if the estimated soc is high. Provide a configurable level for the
estimated SOC below which, the calculated soc can go to 0%.

Change-Id: Ie77b52ed59ba138efca86b840dbd60a38ca81d86
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>