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>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
diff --git a/board/mediatek/mt7628/MAINTAINERS b/board/mediatek/mt7628/MAINTAINERS
new file mode 100644
index 0000000..032fd0e
--- /dev/null
+++ b/board/mediatek/mt7628/MAINTAINERS
@@ -0,0 +1,7 @@
+MT7628_RFB BOARD
+M:	Weijie Gao <weijie.gao@mediatek.com>
+S:	Maintained
+F:	board/mediatek/mt7628
+F:	include/configs/mt7628.h
+F:	configs/mt7628_rfb_defconfig
+F:	arch/mips/dts/mediatek,mt7628-rfb.dts