drm/i915: Read out hrawclk from CCK on vlv/chv

Currently we assume that hrawclk is 200MHz on VLV/CHV. That should
be true always, but just to avoid such asumptions we can read out the
actual frequency from CCK.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1456932138-14004-5-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index dd9118b..62d36a7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -178,7 +178,8 @@
 static int
 intel_vlv_hrawclk(struct drm_i915_private *dev_priv)
 {
-	return 200000;
+	return vlv_get_cck_clock_hpll(dev_priv, "hrawclk",
+				      CCK_DISPLAY_REF_CLOCK_CONTROL);
 }
 
 static int