hwc: fix aspect ratio calculations

- Make aspectratio calculations independent of ext dpy w/h
- pass hwc_rect_t to getAspectRatioPosition function instead of
  x, y, w, h
- overload getAspectRatioPosition func to return the upscaled
  or transformed position for a particular display based on the
  values set by SurfaceFlinger

Change-Id: I0be9b2b4b030bdd8e69dc1493dc8cbac31918c27
3 files changed