drm/amd/display: Use TPS4 instead of CP2520_3 for phy pattern 7

[Description]
We originally use TPS4 phy test pattern for test pattern 7.
On RV we switched to a new method to use CP2520.
CP2520 should produce the same result.
However in reality, it fails DP PHY automation test.
We use the original method instead.
Signed-off-by: Wenjing Liu <Wenjing.Liu@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -1756,7 +1756,7 @@ static void dp_test_send_phy_test_pattern(struct dc_link *link)
 		test_pattern = DP_TEST_PATTERN_CP2520_2;
 		break;
 	case PHY_TEST_PATTERN_CP2520_3:
-		test_pattern = DP_TEST_PATTERN_CP2520_3;
+		test_pattern = DP_TEST_PATTERN_TRAINING_PATTERN4;
 		break;
 	default:
 		test_pattern = DP_TEST_PATTERN_VIDEO_MODE;