power: supply: max17042_battery: Fix compiler warning

Fix drivers/power/supply/max17042_battery.c:1059:6:
warning: 'acpi_id' may be used uninitialized in this function.

No idea why my gcc version did not catch this.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>