drm/amd/display: Avoid virtual stream encoder if not explicitly requested

Virtual stream encoder should not be a free match for thunderbolt or
usbc, and thus should be avoided.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/resource/dcn10/dcn10_resource.c

@@ -1250,7 +1250,10 @@ struct stream_encoder *dcn10_find_first_free_match_stream_enc_for_link(
 			/* Store first available for MST second display
 			 * in daisy chain use case
 			 */
+
+			if (pool->stream_enc[i]->id != ENGINE_ID_VIRTUAL)
 				j = i;
+
 			if (link->ep_type == DISPLAY_ENDPOINT_PHY && pool->stream_enc[i]->id ==
 					link->link_enc->preferred_engine)
 				return pool->stream_enc[i];