ARM: dts: aspeed: bletchley: Enable mdio0 bus

Enable mdio0 bus based on DVT schematic.

TODO: Add Marvell 88E6191 Switch

Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
Reviewed-by: Patrick Williams <patrick@stwcx.xyz>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20220509151118.4899-4-potin.lai.pt@gmail.com


Signed-off-by: Joel Stanley <joel@jms.id.au>