dt-bindings: arm: mediatek: add bindings for mediatek MT7623a SoC Platform

This adds DT binding documentation for Mediatek MT7623a
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/arm/mediatek.txt

@@ -14,6 +14,7 @@ compatible: Must contain one of
    "mediatek,mt6797"
    "mediatek,mt7622"
    "mediatek,mt7623" which is referred to MT7623N SoC
+   "mediatek,mt7623a"
    "mediatek,mt8127"
    "mediatek,mt8135"
    "mediatek,mt8173"