Merge tag 'drm-intel-fixes-2015-05-13' of git://anongit.freedesktop.org/drm-intel into drm-fixes

fix one gpu hang on resume.

* tag 'drm-intel-fixes-2015-05-13' of git://anongit.freedesktop.org/drm-intel:
  drm/i915: Avoid GPU hang when coming out of s3 or s4