drm/amd/display: reset dpcd_cap.dpcd_rev for passive dongle.

[why]
currently dc has never reset this dpcd_cap.dpcd_rev.

[how]
ideally  we should reset this before redo detection.
change the passive dongle only for now to reduce the impact.
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -541,6 +541,7 @@ static void link_disconnect_sink(struct dc_link *link)
 	}
 
 	link->dpcd_sink_count = 0;
+	//link->dpcd_caps.dpcd_rev.raw = 0;
 }
 
 static void link_disconnect_remap(struct dc_sink *prev_sink, struct dc_link *link)
@@ -742,6 +743,7 @@ static bool detect_dp(struct dc_link *link,
 								sink_caps,
 								audio_support);
 		link->dpcd_caps.dongle_type = sink_caps->dongle_type;
+		link->dpcd_caps.dpcd_rev.raw = 0;
 	}
 
 	return true;