SurfaceTexture: fix transform matrix computation.

This change fixes the transform matrix computation in SurfaceTexture
when a crop rectangle is specified by the image producer.  It also adds
a test for this case as well as a basic test for the uncropped case.

Bug: 4070775
Change-Id: I1481c9ce9d08fe7f2bff86d3afdeab7d4002b157