AOD: Fix time tick alarm registration

Fixes an issue where canceling the time tick
alarm was not done properly, which then prevented
the alarm from being scheduled again.

Change-Id: I233f6227eabc65ea1cd13e7c53930573fb552126
Fixes: 36506772
Test: runtest -x packages/SystemUI/tests/src/com/android/systemui/doze/DozeUiTest.java