drm/i915: Actually attach the tv_format property to the SDVO connector

Attach the tv_format property to the SDVO connector instead of passing
a '0' in place of the pointer to the property. This got broken when
the SDVO connector properties were converted to atomic.

We can thank sparse for catching this:
drivers/gpu/drm/i915/intel_sdvo.c:2742:75: warning: Using plain integer as NULL pointer

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 630d30a4ee27 ("drm/i915: Convert intel_sdvo connector properties to atomic.")
Link: http://patchwork.freedesktop.org/patch/msgid/20170615172308.10121-1-ville.syrjala@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -2739,7 +2739,8 @@ static bool intel_sdvo_tv_create_property(struct intel_sdvo *intel_sdvo,
 				i, tv_format_names[intel_sdvo_connector->tv_format_supported[i]]);
 
 	intel_sdvo_connector->base.base.state->tv.mode = intel_sdvo_connector->tv_format_supported[0];
-	drm_object_attach_property(&intel_sdvo_connector->base.base.base, 0, 0);
+	drm_object_attach_property(&intel_sdvo_connector->base.base.base,
+				   intel_sdvo_connector->tv_format, 0);
 	return true;
 
 }