net: dsa: mv88e6xxx: fix usable ports on 88e6020

The switch has 4 ports with 2 internal PHYs, but ports are numbered up
to 6, with ports 0, 1, 5 and 6 being usable.

Fixes: 71d94a432a15 ("net: dsa: mv88e6xxx: add support for MV88E6020 switch")
Signed-off-by: Michael Krummsdorf <[e-mail]>
Signed-off-by: Matthias Schiffer <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/mv88e6xxx/chip.c

···
 		.family = MV88E6XXX_FAMILY_6250,
 		.name = "Marvell 88E6020",
 		.num_databases = 64,
-		.num_ports = 4,
+		/* Ports 2-4 are not routed to pins
+		 * => usable ports 0, 1, 5, 6
+		 */
+		.num_ports = 7,
 		.num_internal_phys = 2,
+		.invalid_port_mask = BIT(2) | BIT(3) | BIT(4),
 		.max_vid = 4095,
 		.port_base_addr = 0x8,
 		.phy_base_addr = 0x0,