Bluetooth : Fix for the unwanted exit from the BTApp

Commenting the system.exit call in the cleanup as this
is causing major issues in cleanup.Next time BT is turned
on, it crashes at any abrupt point since lock is still
held due to exit of application.

Change-Id: Ie42bd6b1c0654077aa13e375798ff40567c89aaa
CRs-fixed: 718214