drm/i915: Only ignore eDP ports that are connected

If the VBT says that a certain port should be eDP (and hence fused off
from HDMI), but in reality it isn't, we need to try and acquire the HDMI
connection instead. So only trust the VBT edp setting if we can connect
to an eDP device on that port.

Fixes: d2182a6608 (drm/i915: Don't register HDMI connectors for eDP ports on VLV/CHV)
References: https://bugs.freedesktop.org/show_bug.cgi?id=96288
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Phidias Chiang <phidias.chiang@canonical.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464766070-31623-1-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9b5f663..ebe7b34 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1312,7 +1312,7 @@
 void intel_csr_ucode_resume(struct drm_i915_private *);
 
 /* intel_dp.c */
-void intel_dp_init(struct drm_device *dev, i915_reg_t output_reg, enum port port);
+bool intel_dp_init(struct drm_device *dev, i915_reg_t output_reg, enum port port);
 bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 			     struct intel_connector *intel_connector);
 void intel_dp_set_link_params(struct intel_dp *intel_dp,