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_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 42ceb15..ca372ab 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -2244,6 +2244,7 @@
 	}
 
 	connector = &intel_connector->base;
+	connector->polled = DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT;
 	encoder->encoder_type = DRM_MODE_ENCODER_TMDS;
 	connector->connector_type = DRM_MODE_CONNECTOR_DVID;
 
@@ -2310,6 +2311,7 @@
                 return false;
 
         connector = &intel_connector->base;
+	connector->polled = DRM_CONNECTOR_POLL_CONNECT;
         encoder->encoder_type = DRM_MODE_ENCODER_DAC;
         connector->connector_type = DRM_MODE_CONNECTOR_VGA;
         sdvo_connector = intel_connector->dev_priv;