drm/i915: Kill intel_prepare_ddi()

Move the ddi buffer translation programming to occur from the encoder
.pre_enable() hook, for just the ddi port we are enabling. Previously
we used to reprogram the translations for all ddi ports during
init and during power well enabling.

v2: s/intel_prepare_ddi_buffers/intel_prepare_ddi_buffer/ (Daniel)
    Resolve conflicts due to  dev_priv->atomic_cdclk_freq

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-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 32de7e4..e27954d 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1025,7 +1025,7 @@
 /* intel_ddi.c */
 void intel_ddi_clk_select(struct intel_encoder *encoder,
 			  const struct intel_crtc_state *pipe_config);
-void intel_prepare_ddi(struct drm_device *dev);
+void intel_prepare_ddi_buffer(struct intel_encoder *encoder);
 void hsw_fdi_link_train(struct drm_crtc *crtc);
 void intel_ddi_init(struct drm_device *dev, enum port port);
 enum port intel_ddi_get_encoder_port(struct intel_encoder *intel_encoder);