BLE: Fix NPE during start advertising

Use case:
Open any app that performs advertising.

Expected result:
BLE should Start advertisement.

Observed result :
Observed force close in BA App.

Fix:
set zero into parcel if transport
discovery data is empty.

Test: BLE Start advertisement successes after performing above use case.

CRs-Fixed: 2304532
Change-Id: Ica730f8d22367864308412621a8d87e625198bec