drm/i915: propagate errors from intel_dp_init_connector

In case we detect a "ghost eDP", intel_edp_init_connector frees both
the connector and encoder and then returns. On Haswell, intel_ddi_init
then tries to use the freed encoder on the HDMI initialization path
since the following commit:

commit 21a8e6a4853b2ed39fa4c5188a710f2cf1b92026
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Apr 10 23:28:35 2013 +0200
    drm/i915: don't setup hdmi for port D edp in ddi_init

So now on intel_ddi_init we check for the "ghost eDP" case and return
without trying to initialize HDMI. This way we won't try to read the
freed "intel_encoder" struct in the next "if" statement.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Zoltan Nyul <zoltan.nyul@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index ffe9d35..9ddbe3b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -586,7 +586,7 @@
 extern bool intel_is_dual_link_lvds(struct drm_device *dev);
 extern void intel_dp_init(struct drm_device *dev, int output_reg,
 			  enum port port);
-extern void intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
+extern bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 				    struct intel_connector *intel_connector);
 extern void intel_dp_init_link_config(struct intel_dp *intel_dp);
 extern void intel_dp_start_link_train(struct intel_dp *intel_dp);