dt-bindings: net: mscc,vsc7514-switch: convert txt bindings to yaml

Convert existing txt bindings to yaml format.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220304103225.111428-1-clement.leger@bootlin.com