SF: move setupHwComposer logic to FE function

One step towards separating FE from BE.  The logic that
traditionally has been in setupHwComposer will be in
a function named calculateWorkingSet as the function
named setUpHwComposer will handle different functionality.

Bug: 112259502
Test: cts -m CtsViewTestCases
      SurfaceFlinger_test
      vrflinger_test

Change-Id: If4c2735898969ab15de42cbd9eb5f08a7a26b545