Telephony: Ignore events on a destroyed phone

It is possible to receive responses from RIL after phone has released
it's references. Ignore events in such cases, since those events no
longer make sense, and some phone members have been de-initialized.

Make CallTrackers notify UI when ending calls in dispose, since
it has already unregistered, and won't receive the CALL_STATE_CHANGED

Change-Id: I5d8fd9ce3f74b9ae9b5b645565bd24d11be0aebc
CRs-Fixed: 228731, 228005, 415801, 350739