drm/fbdev: rework output polling to be back in the core. (v4)

After thinking it over a lot it made more sense for the core to deal with
the output polling especially so it can notify X.

v2: drop plans for fake connector - per Michel's comments - fix X patch sent to xorg-devel, add intel polled/hpd setting, add initial nouveau polled/hpd settings.

v3: add config lock take inside polling, add intel/nouveau poll init/fini calls

v4: config lock was a bit agressive, only needed around connector list reading.
otherwise it could re-enter.

glisse: discard drm_helper_hpd_irq_event

v3: Reviewed-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3230e8d..df931f7 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -235,5 +235,5 @@
 extern int intel_overlay_attrs(struct drm_device *dev, void *data,
 			       struct drm_file *file_priv);
 
-void intelfb_hotplug(struct drm_device *dev, bool polled);
+extern void intel_fb_output_poll_changed(struct drm_device *dev);
 #endif /* __INTEL_DRV_H__ */