net: dsa: felix: allow PHY_INTERFACE_MODE_INTERNAL on port 5

The Felix switch has 6 ports, 2 of which are internal.
Due to some misunderstanding, my initial suggestion for
vsc9959_port_modes[]:
https://patchwork.kernel.org/project/netdevbpf/patch/20220129220221.2823127-10-colin.foster@in-advantage.com/#24718277

got translated by Colin into a 5-port array, leading to an all-zero port
mode mask for port 5.

Fixes: acf242fc ("net: dsa: felix: remove prevalidate_phy_mode interface")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220318195812.276276-1-vladimir.oltean@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/ocelot/felix_vsc9959.c

@@ -37,6 +37,7 @@ static const u32 vsc9959_port_modes[VSC9959_NUM_PORTS] = {
 	VSC9959_PORT_MODE_SERDES,
 	VSC9959_PORT_MODE_SERDES,
 	OCELOT_PORT_MODE_INTERNAL,
+	OCELOT_PORT_MODE_INTERNAL,
 };
 
 static const u32 vsc9959_ana_regmap[] = {