drm/amd/display: Use stream_enc to get head pipe.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -887,7 +887,7 @@ struct pipe_ctx *resource_get_head_pipe_for_stream(
 	int i;
 	for (i = 0; i < res_ctx->pool->pipe_count; i++) {
 		if (res_ctx->pipe_ctx[i].stream == stream &&
-				!res_ctx->pipe_ctx[i].top_pipe) {
+				res_ctx->pipe_ctx[i].stream_enc) {
 			return &res_ctx->pipe_ctx[i];
 			break;
 		}