Simplify and clean up legacy decisions

During the HWC 0.x evolution, some fields were left optional or
organized strangely to avoid breaking backwards compatibility. Since
we're breaking it in the transition to HWC 1.0 anyway, we can clean
these up a little.

* The current callbacks are now registered immediately after the
  device is opened and guaranteed to be present, so the implementation
  can rely on them being present.

* The hwc_methods_t structure is gone, with its two methods folded
  into the main hwc_composer_device_1_t.

* All methods and callbacks are now required except dump(). New
  methods and callbacks we add in the future will still be optional
  for backwards compatibility.

Change-Id: I5d58774a5144016993c12df3dd6ad2a5d746bee9
1 file changed