dt-bindings: net: Convert FMan MAC bindings to yaml

This converts the MAC portion of the FMan MAC bindings to yaml.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>