Fix Skia pipeline readback for non-portrait mode

Apply correctly the image transform matrix passed to
SkiaOpenGLReadback::copyImageInto.
This is fixing 13 of 14 failing android.view.cts.PixelCopyTest
tests (the last failing test is caused by missing wide gamut
support).

Test: Ran CtsViewTestCases CTS tests for Skia and HWUI pipelines.
Bug: 63629735
Change-Id: I67fb06968e21f9aa88973c076870b5557f15d483