Don't re-add SurfaceSyncGroup to same parent

The scenario that caused the crash was the following:
1. SyncGroup C adds A so A's parent is now C
2. C adds B so B's parent is now C
3. New SyncGroup D adds A
4. A's parent is C so D needs to add C.
   C's old parent was null, new parent is now D.
5. D adds B
6. B's parent is C so D needs to add C. C's old parent was D, new parent
   is D. This causes the stack overflow.

Ensure that the old parent and new parent aren't the same when trying to
call newParent.addToSync(oldParent)

Test: Device that was crashing no longer does.
Test: SurfaceSyncGroupTest#testAddToSameParentNoCrash
Fixes: 262662555
Change-Id: Ifce471068c01711260042aee954f1e7a523d386e