drm/amd/display: Clear encoder assignment for copied streams

[Why]
When copying a stream, the encoder assigned to it is copied too.
Encoder assignment should only happen when executing the encoder
assignment function link_encs_assign().

[How]
Clear the link encoder pointer for copied stream.
Reviewed-by: Meenakshikumar Somasundaram <Meenakshikumar.Somasundaram@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Agustin Gutierrez Sanchez <agustin.gutierrez@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@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_stream.c

@@ -202,6 +202,10 @@ struct dc_stream_state *dc_copy_stream(const struct dc_stream_state *stream)
 	new_stream->stream_id = new_stream->ctx->dc_stream_id_count;
 	new_stream->ctx->dc_stream_id_count++;
 
+	/* If using dynamic encoder assignment, wait till stream committed to assign encoder. */
+	if (new_stream->ctx->dc->res_pool->funcs->link_encs_assign)
+		new_stream->link_enc = NULL;
+
 	kref_init(&new_stream->refcount);
 
 	return new_stream;