msm8953-common: Remove power-off alarm stuff from init extension

 * CAF's init.qcom.early_boot.sh checks /persist/alarm/powerOffAlarmSet
   before setting ro.alarm_boot, but on Oreo nothing writes to that
   file, thus code is never executed and the prop is never set.
 * Without ro.alarm_boot=true, the system will boot normally instead of
   boot to min framework even on rtc, and alarm will ring after boot
   completed.

Change-Id: Ie4d30358314337c229a66a16195f675198ef7d52