mlxsw: Bump firmware version to 13.2000.2308

The version adds support for querying port module type. It will be used
by a followup patch set from Jiri to make port split code more generic.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>