alarmtimer : Remove power_on_alarm_init

power_on_alarm_init is for some special mode like power off charging
mode. It is to read the rtc alarm value when boot-up. When resume
happens, set the value back to rtc register.

But now qtimer is used to wake-up from suspend state instead of RTC_ALARM.
Rtc alarm will not be canceled after suspend and resume for all kind of
modes.

So remove power_on_alarm_init and set power off alarm work in alarmtimer
resume.

CRs-Fixed: 2070501
Change-Id: I2aaf0a56b7bf5cf66b1f554d09d8e11b84cba58f
Signed-off-by: Mao Jinlong <c_jmao@codeaurora.org>