qpnp-fg-gen3: add support to configure CC_CV threshold runtime

There is a requirement where an user wants to set CC_CV threshold
runtime so that it can be adjusted whenever the float voltage is
changed.

Add support for it via POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE
property.

Change-Id: I7fcb75f69f12fc2baf8e270a13cad6686c793bf9
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>