misc drm core patches.

* tag 'topic/drm-misc-2015-05-06' of git://anongit.freedesktop.org/drm-intel:
  drm: simplify master cleanup
  drm: simplify authentication management
  drm: drop unused 'magicfree' list
  drm: fix a memleak on mutex failure path
  drm/atomic-helper: Really recover pre-atomic plane/cursor behavior
  drm/qxl: Fix qxl_noop_get_vblank_counter()
  drm: Zero out invalid vblank timestamp in drm_update_vblank_count. (v2)
  drm: Prevent invalid use of vblank_disable_immediate. (v2)
  drm/vblank: Fixup and document timestamp update/read barriers
  DRM: Don't re-poll connector for disconnect
  drm: Fix for DP CTS test 4.2.2.5 - I2C DEFER handling
  drm: Fix the 'native defer' message in drm_dp_i2c_do_msg()
  drm/atomic-helper: Don't call atomic_update_plane when it stays off