power: qpnp-fg-gen4: Enable parallel charging current measurement

Fuel gauge (FG) needs to measure the battery charging current
flowing through both main charger and parallel charger to
calculate the state of charge (SOC) accurately. Enable parallel
charging current measurement to do that.

Change-Id: I6111560f7cc6d831b6292b7322c94e85e73ff8bd
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>