Update call object after connection dispose.

In current implementation, after phone type switch during active call,
although all connections corresponding to previous phone type are
disposed corresponding GsmCdmaCall objects(like mForegroundCall)
are still in active state resulting in user not able to make MO
call after phone type switch.

Hence with this fix, whenever connection is disposed, update its
parent call object so that it can update call state appropriately.

Change-Id: Icde0226221f7bfa7cd5d24e21b5a92bef1aabda4
CRs-Fixed: 1078508