drm/i915: Use cached cdclk value

Rather than reading out the current cdclk value use the cached value we
have tucked away in dev_priv.

v2: Rebased to the latest
v3: Rebased to the latest
v4: Fix for patch style problems

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>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index fb5c01e..f73da99 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -710,7 +710,8 @@
 		return 0;
 
 	if (intel_dig_port->port == PORT_A) {
-		return DIV_ROUND_UP(dev_priv->display.get_display_clock_speed(dev), 2000);
+		return DIV_ROUND_UP(dev_priv->cdclk_freq, 2000);
+
 	} else {
 		return DIV_ROUND_UP(intel_pch_rawclk(dev), 2);
 	}
@@ -725,7 +726,7 @@
 	if (intel_dig_port->port == PORT_A) {
 		if (index)
 			return 0;
-		return DIV_ROUND_CLOSEST(dev_priv->display.get_display_clock_speed(dev), 2000);
+		return DIV_ROUND_CLOSEST(dev_priv->cdclk_freq, 2000);
 	} else if (dev_priv->pch_id == INTEL_PCH_LPT_DEVICE_ID_TYPE) {
 		/* Workaround for non-ULT HSW */
 		switch (index) {