Initializing the SDP event message pointer before sending

Use case: Crash while copying SDP results in case of SDP
ServiceSearchAttributeRequest failure

Steps : Repeated connection-disconnection with multiple devices

Failure: Crash while copying SDP results

Root cause: In case of SDP_ServiceSearchAttributeRequest failure,
garbage value sent for discovery result structure due to improper
initialization

Fix: Initialize the discovery result structure to zero before
sending

Test: code compilation.

Change-Id: I46d92d6262bae3b5def5401270465a3a06468c1a