power: supply: axp288_fuel_gauge: Do not register FG on ECS EF20EA

The ECS EF20EA laptop ships an AXP288 but it is actually using a
different, separate FG chip for AC and battery monitoring. On this
laptop we need to keep using the regular ACPI driver and disable the
AXP288 FG to avoid reporting two batteries to userspace.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>