Merge tag 'drm-intel-fixes-2016-04-21' of git://anongit.freedesktop.org/drm-intel...

Hi Dave, fixes all around, all but one are cc: stable material, the most
important ones are likely the Skylake hang fixes from Mika.

* tag 'drm-intel-fixes-2016-04-21' of git://anongit.freedesktop.org/drm-intel:
  drm/i915: Use fw_domains_put_with_fifo() on HSW
  drm/i915: Force ringbuffers to not be at offset 0
  drm/i915: Adjust size of PIPE_CONTROL used for gen8 render seqno write
  drm/i915/skl: Fix spurious gpu hang with gt3/gt4 revs
  drm/i915/skl: Fix rc6 based gpu/system hang
  drm/i915/userptr: Hold mmref whilst calling get-user-pages
  drm/i915: Fixup the free space logic in ring_prepare
  drm/i915/skl+: Use plane size for relative data rate calculation