drm/i915: Clear pfit registers when not used by any outputs

... otherwise the panel-fitter may be left enabled with random settings
and cause unintended filtering (i.e. blurring of native modes on external
panels).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=31942
Reported-and-tested-by: Ben Kohler <bkohler@gmail.com>
Tested-by: Ciprian Docan <docan@eden.rutgers.edu>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 21551fe..e52c612 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -237,7 +237,7 @@
 extern void intel_dvo_init(struct drm_device *dev);
 extern void intel_tv_init(struct drm_device *dev);
 extern void intel_mark_busy(struct drm_device *dev, struct drm_gem_object *obj);
-extern void intel_lvds_init(struct drm_device *dev);
+extern bool intel_lvds_init(struct drm_device *dev);
 extern void intel_dp_init(struct drm_device *dev, int dp_reg);
 void
 intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,