hwc: Add binder interface to get the visibleRegion

- This binder interface can be used by clients to know the
  active visible region for a display(pri/ext/virt)
- When external orientation is used, return the destFrame of
  the FrameBuffer layer, as its the viewFrame

Change-Id: I7cfd149c76c16b9a3031103c89b1932d44bcbecd
hwc: Reset layer-to-rotator map and fences on configuration failure

When a rotator or mdp configuration for a display fails, reset the
layer-to-rotator mappings for that display and reset the release
fences for the rotator objects used for that display.

Note: The rotator itself is offline and not tied to any mixer. It is
from the mappings that we deduce which rotator object was used for
layers of which display. Also we don't delete rotator objects held
for a specific display, since during stability runs, failures could
repeat each round and we end up allocating and deallocating memory
unnecessarily. The rotator objects will be deleted automatically
when not required anymore.

Change-Id: I9a67f02574be30be3b96b3575f60530cb1c89e10