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 [1]
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>

drivers/net/dsa/mt7530.c

@@ -2577,7 +2577,7 @@ static void mt7988_mac_port_get_caps(struct dsa_switch *ds, int port,
 
 	switch (port) {
 	/* Ports which are connected to switch PHYs. There is no MII pinout. */
-	case 0 ... 4:
+	case 0 ... 3:
 		__set_bit(PHY_INTERFACE_MODE_INTERNAL,
 			  config->supported_interfaces);
 		break;