Add support for MT7622 reference board

This adds a general board file based on MT7622 SoCs from MediaTek.
This commit is adding the basic boot support for the MT7622 rfb.

Signed-off-by: Sam Shih <sam.shih@mediatek.com>
Reviewed-by: Ryder Lee <ryder.lee@mediatek.com>
Tested-by: Frank Wunderlich <frank-w@public-files.de>
diff --git a/board/mediatek/mt7622/MAINTAINERS b/board/mediatek/mt7622/MAINTAINERS
new file mode 100644
index 0000000..a3e0e75
--- /dev/null
+++ b/board/mediatek/mt7622/MAINTAINERS
@@ -0,0 +1,6 @@
+MT7622
+M:	Sam Shih <sam.shih@mediatek.com>
+S:	Maintained
+F:	board/mediatek/mt7622
+F:	include/configs/mt7622.h
+F:	configs/mt7622_rfb_defconfig