Fix local disconnect reason code

For local disconnect of device, BTA_GATTC_CLOSE_EVT was sent
with reason code 0 rather than GATT_CONN_TERMINATE_LOCAL_HOST.

Fixed the issue by sending reason code
GATT_CONN_TERMINATE_LOCAL_HOST for local disconnect case.

Test: Verified local disconnect reason code is sent as
      GATT_CONN_TERMINATE_LOCAL_HOST and not 0
Change-Id: I964dc7480dae4a0840450652992eaf48ca439e2f