Alarm: Support devices using timerfd without CLOCK_POWEROFF_ALARM

timerfd CLOCK_POWEROFF_ALARM is patch from qcom for power off alarm
support in qcom devices. Some old devices or non-qcom devices
does not support CLOCK_POWEROFF_ALARM in timerfd that results in
init_timerfd function fails.

Use fallback mechanism if devices does not support CLOCK_POWEROFF_ALARM
in timerfd use CLOCK_REALTIME instead.

Change-Id: I166f2a3cea21cd6dc67a520e268315076dc4356a