mips: mtmips: add support for mt7628-rfb

This patch adds support for mt7628 reference board. SPL_DM and DT are not
enabled for SPL to save about 17KiB for u-boot-spl.bin.

Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/board/mediatek/mt7628/board.c b/board/mediatek/mt7628/board.c
new file mode 100644
index 0000000..f837a06
--- /dev/null
+++ b/board/mediatek/mt7628/board.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 MediaTek Inc. All Rights Reserved.
+ *
+ * Author: Weijie Gao <weijie.gao@mediatek.com>
+ */
+
+#include <common.h>