os/pm: fix pm_timedsuspend cancel

[gSahitya-samsung]

When a thread call pm_timedsuspend multiple times within timer expiration, then pm_timedsuspend doesn't stoping the timer, instead it was rasing error. Now when pm_timedsuspend call multiple times within timer expiration, then it changes timer duration to remain suspended for given time if it is greater than current expiration time. If application provide zero time interval, then it cancel the timer immediately and resume the suspended domain.

[ewoodev]

@r-prabu @kishore-sn Could you review and merge?