power: qpnp-fg: add support for configuring the CC_CV setpoint

When the float voltage adjustment algorithm is active, the CC_CV
(Constant Charge to Constant Voltage) setpoint needs to be set
closer to the float voltage. Add support for configuring it.

CRs-Fixed: 793257
Change-Id: I027ad3127d8ce56d132a9d7dfe5b7057b73f0650
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>