Fix SF hint sessions for virtual multi-display case

Currently timing for hint sessions in SurfaceFlinger do not work for
multi-display case with virtual displays (eg: Android Auto). This
patch fixes that by tracking true sf present completion time to
supplement hwc time tracking in the sf main thread deadline case.

Bug: b/241465879

Test: manual

Change-Id: I169dd4f4afd2223ed0a648440d5f59dc19dc07f6