After "commit f0e1c5e init vcpu host stack when reset vcpu", SOS resume form S3
wants to schedule to vcpu_thread not the point where SOS enter S3. So we should
schedule to idel first then reschedule to execute vcpu_thread.
Tracked-On: #3387
Signed-off-by: Li, Fei1 <fei1.li@intel.com>