If the return value is non-zero here, DoTimer() will automatically rearm
the timer for the new (relative) delay. 'soonest' is in absolute time,
so subtract off 'now' and return that.
Reviewed-by: Robert Morell <rmorell@nvidia.com>
Tested-by: Robert Morell <rmorell@nvidia.com>
Signed-off-by: Adam Jackson <ajax@redhat.com>