Merge tag 'drm-intel-fixes-2016-02-22' of git://anongit.freedesktop.org/drm-intel...

This is a bit large, but it really helps Skylake bugs we are seeing
on a number of laptops.

Most of the commits are quite similar, ensuring the display power
doesn't vanish under us during hardware access. Also do note that it's
not just Skylake that's affected.

* tag 'drm-intel-fixes-2016-02-22' of git://anongit.freedesktop.org/drm-intel:
  drm/i915/gen9: Verify and enforce dc6 state writes
  drm/i915/gen9: Check for DC state mismatch
  drm/i915/skl: Ensure HW is powered during DDB HW state readout
  drm/i915/lvds: Ensure the HW is powered during HW state readout
  drm/i915/hdmi: Ensure the HW is powered during HW state readout
  drm/i915/dsi: Ensure the HW is powered during HW state readout
  drm/i915/dp: Ensure the HW is powered during HW state readout
  drm/i915: Ensure the HW is powered when accessing the CRC HW block
  drm/i915/ddi: Ensure the HW is powered during HW state readout
  drm/i915/crt: Ensure the HW is powered during HW state readout
  drm/i915: Ensure the HW is powered during HW access in assert_pipe
  drm/i915: Ensure the HW is powered when disabling VGA
  drm/i915/ibx: Ensure the HW is powered during PLL HW readout
  drm/i915: Ensure the HW is powered during display pipe HW readout
  drm/i915: Add helper to get a display power ref if it was already enabled