power: wakeup_reason: fix suspend time reporting

power: wakeup_reason: fix suspend time reporting

Suspend time reporting Change-Id: I2cb9a9408a5fd12166aaec11b935a0fd6a408c63
(Power: Report suspend times from last_suspend_time), is broken on 3.16+
kernels because get_xtime_and_monotonic_and_sleep_offset() hrtimer helper
routine is removed from kernel timekeeping.

The replacement helper routines ktime_get_update_offsets_{tick,now}()
are private to core kernel timekeeping so we can't use them, hence using
ktime_get() and ktime_get_boottime() instead and sampling the time twice.

Idea is to use Monotonic boottime offset to calculate total time spent
in last suspend state and CLOCK_MONOTONIC to calculate time spent in
last suspend-resume process.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>