SAP: Fix following issues in SAP Code

- Remove redundant code calling in intiSocket() to call
  closeServerSocket() as it will anyways be called from
  closeService(). Redundant code can lead to ANR's when
  starting/stopping service or BT on/off is done
  various times.
- Add check to prevent unregistering receiver when it
  is not registered.
- Add null checks to prevent pointer dereference.

CRs-Fixed: 952309
Change-Id: Ie364062243dc1902d49c4a858b6c11336789e8cc