drm/amd/display: Set LTTPR mode to non-LTTPR if no repeaters found

[WHY]
If no repeaters are found, we do not need or want to attempt to
link-train repeaters, as this could cause bugs.
Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Acked-by: Bindu Ramamurthy <bindur12@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3582,6 +3582,8 @@ static bool retrieve_link_cap(struct dc_link *link)
 				link->dpcd_caps.lttpr_caps.revision.raw >= 0x14);
 		if (is_lttpr_present)
 			CONN_DATA_DETECT(link, lttpr_dpcd_data, sizeof(lttpr_dpcd_data), "LTTPR Caps: ");
+		else
+			link->lttpr_mode = LTTPR_MODE_NON_LTTPR;
 	}
 
 	if (!is_lttpr_present)