Add null check to avoid exception after L2CAP psm assigned

Use case: BT will get crash in SNS testing.

steps: SNS testing BT ON/OFF.

Failure: Crash is observed.

Root Cause: If the number of supported services increased,
larger service record array is required. Smaller array is
resulting in out of record error causing L2CAP deregister.

Fix: Check added to avoid null pointer exception if null
is returned while fetching sock from id. Also cleanup of
SDP and security records done during BT turning Off.

Change-Id: I2e77127262119cabf2c372f894427dcdf3350e80