arm: dts: mt7623: add port@5 as CPU port

On the MT7623AI SoC and Bananapi BPI-R2, port 5 of the MT7530 switch is
connected to the second MAC of the SoC as a CPU port. Add the port and set
up the second MAC on the bindings.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Link: https://lore.kernel.org/r/20230210182505.24597-6-arinc.unal@arinc9.com


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