drm/i915: Check for CPT and not !IBX in ironlake_disable_pch_transcoder()

ironlake_enaable_pch_transcoder() checks for CPT to see if it should
enable the timing override chicken bit, but
ironlake_disable_pch_transcoder() checks for !IBX to see if it should
clear the same bit. Change ironlake_disable_pch_transcoder() to check
for CPT as well to keep the two sides consistent.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446146763-31821-8-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/gpu/drm/i915/intel_display.c

@@ -2059,7 +2059,7 @@ static void ironlake_disable_pch_transcoder(struct drm_i915_private *dev_priv,
 	if (wait_for((I915_READ(reg) & TRANS_STATE_ENABLE) == 0, 50))
 		DRM_ERROR("failed to disable transcoder %c\n", pipe_name(pipe));
 
-	if (!HAS_PCH_IBX(dev)) {
+	if (HAS_PCH_CPT(dev)) {
 		/* Workaround: Clear the timing override chicken bit again. */
 		reg = TRANS_CHICKEN2(pipe);
 		val = I915_READ(reg);