dt-bindings: arm: airoha: Add binding for EN7523 SoC and EVB

Add devicetree binding for Airoha EN7523 SoC and evaluation board.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Bert Vermeulen <bert@biot.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20211220211854.89452-3-nbd@nbd.name


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>