libhwc2on1adapter: avoid marking changes if visible regions unchanged

The function setVisibleRegions is always called as part of composition,
shouldn't mark geometry changed if there are no changes in the visible
regions.

Bug: 65019874
Test: run cts -m CtsViewTestCases -t android.view.cts.DisplayRefreshRateTest#testRefreshRate
Change-Id: I3f93431002fc4b691c799f4ae91aa1488849e4a6