Merge tag 'drm-vc4-fixes-2016-06-06' of github.com:anholt/linux into drm-fixes

This pull request brings in vblank/pageflip fixes I had hoped to see
merged before 4.7rc1, plus two new fixes that have come in since then.

* tag 'drm-vc4-fixes-2016-06-06' of github.com:anholt/linux:
  drm/vc4: Make pageflip completion handling more robust.
  drm/vc4: Fix ioctl permissions for render nodes.
  drm/vc4: Return -EBUSY if there's already a pending flip event.
  drm/vc4: Fix drm_vblank_put/get imbalance in page flip path.
  drm/vc4: Fix get_vblank_counter with proper no-op for Linux 4.4+