net: dsa: mt7530: correct port capabilities of MT7988

net: dsa: mt7530: correct port capabilities of MT7988

On the switch on the MT7988 SoC, as shown in Block Diagram 8.1.1.3 on page
125 of "MT7988A Wi-Fi 7 Generation Router Platform: Datasheet (Open
Version) v0.1", there are only 4 PHYs. That's port 0 to 3. Set the case for
ports which connect to switch PHYs to '0 ... 3'.

Port 4 and 5 are not used at all in this design.

Link: https://wiki.banana-pi.org/Banana_Pi_BPI-R4#Documents
Acked-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Link: https://lore.kernel.org/r/20240206-for-netnext-mt7530-improvements-2-v5-6-d7d92a185cb1@arinc9.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>