drm/rockchip: cdn-dp: add more log for video config

In order to analyze some video config failed, add some useful
printouts.
Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1488940077-22297-4-git-send-email-zyw@rock-chips.com

drivers/gpu/drm/rockchip/cdn-dp-reg.c

@@ -671,6 +671,10 @@ int cdn_dp_config_video(struct cdn_dp_device *dp)
 		rem = do_div(symbol, 1000);
 		if (tu_size_reg > 64) {
 			ret = -EINVAL;
+			DRM_DEV_ERROR(dp->dev,
+				      "tu error, clk:%d, lanes:%d, rate:%d\n",
+				      mode->clock, dp->link.num_lanes,
+				      link_rate);
 			goto err_config_video;
 		}
 	} while ((symbol <= 1) || (tu_size_reg - symbol < 4) ||