Remove a change about MSG2 and MSG4 because this is used not only in L2 FAPI simulator but also in real eNB.

Modify not to assert a part in L2 FAPI simulator because it's possible to differ timing(frame, subframe) between eNB and UE.

Change not to watch timing in MSG2 and MSG4 procedure in L2 FAPI simulator because it's possible to differ timing(frame, subframe) between eNB and UE.

Fix for problems that L2sim finishes in case of multiple UEs and UE L2sim keeps wating for a signal.

Fix for problems that eNB keeps waiting for signal of unused thread and eNB_thread_rxtx isn't created.