dt-bindings: arm: mediatek: add support for more mt7623 reference boards

Update binding document for more mt7623[A,N] reference boards being
supported.
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/arm/mediatek.txt

@@ -50,6 +50,15 @@ Supported boards:
 - Reference board variant 1 for MT7622:
     Required root node properties:
       - compatible = "mediatek,mt7622-rfb1", "mediatek,mt7622";
+- Reference board for MT7623a with eMMC:
+    Required root node properties:
+      - compatible = "mediatek,mt7623a-rfb-emmc", "mediatek,mt7623";
+- Reference board for MT7623a with NAND:
+    Required root node properties:
+      - compatible = "mediatek,mt7623a-rfb-nand", "mediatek,mt7623";
+- Reference board for MT7623n with eMMC:
+    Required root node properties:
+      - compatible = "mediatek,mt7623n-rfb-emmc", "mediatek,mt7623";
 - Reference  board for MT7623n with NAND:
     Required root node properties:
       - compatible = "mediatek,mt7623n-rfb-nand", "mediatek,mt7623";