Fixed incorrect state machine transition in data network

After IWLAN handover complete, the source transport PDN clean up
failure shuold not cause the already-handover data network torn
down.

Fix: 225177283
Test: Manual
Merged-In: I09b09408759564fd8464fcc2dff23551fa372848
Change-Id: I09b09408759564fd8464fcc2dff23551fa372848