Add method to get surface dataspace

Add ability to query the dataspace of a FramebufferSurface so that
we can include that in the DisplayDevice dumpsys data.
Test: adb shell dumpsys SurfaceFlinger
Look for DisplayDevice section for dataspace.
Bug: 63146977

Change-Id: I1d30bd48782485a422db7a0a0af1e585bbffd508