Black screen fixes, one for hsw+bdw each and a regression fix for
locking+load detection.
* tag 'drm-intel-fixes-2014-01-13' of git://people.freedesktop.org/~danvet/drm-intel:
drm/i915/bdw: make sure south port interrupts are enabled properly v2
drm/i915: Don't grab crtc mutexes in intel_modeset_gem_init()
drm/i915: fix DDI PLLs HW state readout code