drm/msm/dp: stop link training after link training 2 failed

Each DP link training contains link training 1 followed by link
training 2.  There is maximum of 5 retries of DP link training
before declared link training failed. It is required to stop link
training at end of link training 2 if it is failed so that next
link training 1 can start freshly. This patch fixes link compliance
test  case 4.3.1.13 (Source Device Link Training EQ Fallback Test).

Changes in v10:
--  group into one series

Changes in v11:
-- drop drm/msm/dp: dp_link_parse_sink_count() return immediately if aux read

Fixes: 2e0adc7 ("drm/msm/dp: do not end dp link training until video is ready")
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1642531648-8448-5-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Author: Kuogee Hsieh

drivers/gpu/drm/msm/dp/dp_ctrl.c

@@ -1755,6 +1755,9 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
 				/* end with failure */
 				break; /* lane == 1 already */
 			}
+
+			/* stop link training before start re training  */
+			dp_ctrl_clear_training_pattern(ctrl);
 		}
 	}