power: qpnp-fg-gen4: Get correct float voltage for Rbatt calculation

Currently, when Rbatt is calculated for TTF algorithm, float
voltage from the battery profile is used. In the case of early
taper because of soft JEITA condition, this provides incorrect
values when Vbatt is lower than the original float voltage but
the compensated float voltage is lower. Fix it by getting the
actual float voltage from FV votable in Rbatt calculation.

Change-Id: Ib9f7fccab6d047a1aa00ee0e6ce8118b6a32b3db
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>