drm/i915/dvo: Remove ->mode_set callback

Currently for the i9xx crtc hooks there's nothing between the call to
encoder->mode_set and encoder->pre_enable which touches the hardware.

Therefore, since dvo is only used on gen2, we can just move the hook.
Yay for easy cases!

The only other important thing to check is that the new
->pre_enable hook is idempotent wrt the sw state since now it can be
called multiple times (due to DPMS). It only reads crtc->config but
otherwise leaves it as-is, so we're good.
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dvo.c

@@ -285,7 +285,7 @@ static bool intel_dvo_compute_config(struct intel_encoder *encoder,
 	return true;
 }
 
-static void intel_dvo_mode_set(struct intel_encoder *encoder)
+static void intel_dvo_pre_enable(struct intel_encoder *encoder)
 {
 	struct drm_device *dev = encoder->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -475,7 +475,7 @@ void intel_dvo_init(struct drm_device *dev)
 	intel_encoder->get_hw_state = intel_dvo_get_hw_state;
 	intel_encoder->get_config = intel_dvo_get_config;
 	intel_encoder->compute_config = intel_dvo_compute_config;
-	intel_encoder->mode_set = intel_dvo_mode_set;
+	intel_encoder->pre_enable = intel_dvo_pre_enable;
 	intel_connector->get_hw_state = intel_dvo_connector_get_hw_state;
 	intel_connector->unregister = intel_connector_unregister;