power: qpnp-bms: Clamp CC-based SoC based on voltage

Defaulting to voltage-based SoC is keeping the main coulomb counter based
SoC algorithm from being tested. However, the accuracy issues of the
CC-based SoC algorithm may allow the battery to UVLO or go into early
shutdown.

Clamp the SoC reported based on voltage in order to prevent these
issues. If the voltage is higher than cutoff, then always display
1 or higher SoC. If voltage is lower than cutoff, then always display 0
SoC.

Change-Id: Iccffb7d8a416aa9fdd35c85237e8ac9e3f391354
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>