drm/i915: Convert the ddi cdclk code to get_display_clock_speed

Unify the HSW/BDW/SKL cdclk extraction code to conform to the same
.get_display_clock_speed() mold that all the other platforms
use.

v2: Update due to SKL code getting added

v3: Rebase on top of -nightly (introduction of intel_audio.c) (Mika Kahola)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
[danvet: Add v3 note as suggested by Damien.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index fa4ccb3..e1392e7 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -1792,7 +1792,7 @@
 	linetime = DIV_ROUND_CLOSEST(mode->crtc_htotal * 1000 * 8,
 				     mode->crtc_clock);
 	ips_linetime = DIV_ROUND_CLOSEST(mode->crtc_htotal * 1000 * 8,
-					 intel_ddi_get_cdclk_freq(dev_priv));
+					 dev_priv->display.get_display_clock_speed(dev_priv->dev));
 
 	return PIPE_WM_LINETIME_IPS_LINETIME(ips_linetime) |
 	       PIPE_WM_LINETIME_TIME(linetime);