sf: avoid assumption remote binder is local

We are lucky that a test was passing a remote binder here and that I
happened to reorder elements in BpBinder, since this caused a crash,
where before, 'owner' was getting set to some random bits inside of a
BpBinder object.

Bug: 150904694
Test: move mTrackingUid around in BpBinder, then
    `atest CompositionSamplingListenerTest` passes

Change-Id: I552a669113844a6b7ceaba5a1197fd04ca7e18d5