dt-bindings: Add vendor prefix for Airoha

Add vendor prefix "airoha" for Airoha, a subsidiary of MediaTek

Acked-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/20211220211854.89452-2-nbd@nbd.name


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