drm/amd/display: assign new stream id in dc_copy_stream

[why]
stream id should uniquely identify an instance of stream.
the copy constructor should be treated as a new
stream instance.

[how]
assign a new stream id in this copy constructor.
Signed-off-by: Wenjing Liu <Wenjing.Liu@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -179,6 +179,9 @@ struct dc_stream_state *dc_copy_stream(const struct dc_stream_state *stream)
 	if (new_stream->out_transfer_func)
 		dc_transfer_func_retain(new_stream->out_transfer_func);
 
+	new_stream->stream_id = new_stream->ctx->dc_stream_id_count;
+	new_stream->ctx->dc_stream_id_count++;
+
 	kref_init(&new_stream->refcount);
 
 	return new_stream;