ACPI / battery: abort initialization earlier if acpi_disabled

If ACPI is disabled there's no need to schedule an async function call,
the driver initialization can be aborted earlier in acpi_battery_init().

Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>