do not unbind if the connection has been cleared already

It's possible that during the wait of bind/fetch complete,
the connection to carrier service has been cleared due to clear event e.g,
sim card status change. Then we should not unbind again when handling
bind/fetch timeout event to avoid NPE.

Bug: 131637624
Test: manual
Change-Id: Ie87d7270e7f1094601c97c5e992006d8dcaecb99
1 file changed