dt-bindings: usb: mtk-musb: add MT7623 compatible

Document MT7623 compatible for mtk-musb.

Signed-off-by: Sungbo Eo <mans0n@gorani.run>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210808123840.176738-2-mans0n@gorani.run


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>