drm/i915 fixes for v4.15-rc4
* tag 'drm-intel-fixes-2017-12-14' of git://anongit.freedesktop.org/drm/drm-intel:
drm/i915/fence: Use rcu to defer freeing of irq_work
drm/i915: Stop listening to request resubmission from the signaler kthread
drm/i915: Drop fb reference on load_detect_pipe failure path
drm/i915: Flush pending GTT writes before unbinding