drm/i915: drop helper vtable for sdvo encoder

Completely unused by now. Separate patch in case I've missed a
place somewhere which dereferences the helper vtable but actually
shouldn't do so.

v2: Resolve rebase conflict with Egbert Eich's hpd infrastructure
rework.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -2041,9 +2041,6 @@ done:
 #undef CHECK_PROPERTY
 }
 
-static const struct drm_encoder_helper_funcs intel_sdvo_helper_funcs = {
-};
-
 static const struct drm_connector_funcs intel_sdvo_connector_funcs = {
 	.dpms = intel_sdvo_dpms,
 	.detect = intel_sdvo_detect,
@@ -2784,8 +2781,6 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 	if (intel_sdvo->hotplug_active)
 		intel_encoder->hpd_pin = HPD_SDVO_B ? HPD_SDVO_B : HPD_SDVO_C;
 
-	drm_encoder_helper_add(&intel_encoder->base, &intel_sdvo_helper_funcs);
-
 	intel_encoder->compute_config = intel_sdvo_compute_config;
 	intel_encoder->disable = intel_disable_sdvo;
 	intel_encoder->mode_set = intel_sdvo_mode_set;