CompositionEngine: fix HWC transform calculation

Use the correct display transform in calculateOutputRelativeBufferTransform().
When SF_PRIMARY_DISPLAY_ORIENTATION is set, DisplayDevice only updates the
logical to physical transform; OutputCompositionState.orientation doesn't
change.

Test: - OutputLayerTest.displayInstallOrientationBufferTransformSetTo90
      - Run "dumpsys SurfaceFlinger" on a device with SF_PRIMARY_DISPLAY_ORIENTATION
        set to 90 and verify that the HWC transform is 0 (identity)
      - screencap
Change-Id: I079b5ea22de8d47a7fb7233d01decfbd4b578be8
Merged-In: I079b5ea22de8d47a7fb7233d01decfbd4b578be8