For system without secondary battery, current DSDT will report warning during build time. Add a conditional check to make sure only battery index 0 can return success. TEST=Build pass. Change-Id: Iae12c5d1aa749948ef4025c8b5e60c97e1b747a5 Signed-off-by: Lijian Zhao <lijian.zhao@intel.com> Reviewed-on: https://review.coreboot.org/23661 Reviewed-by: Furquan Shaikh <furquan@google.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Nicolas Boichat <drinkcat@chromium.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org>