mlxsw: switch_ib: Pass valid HW id down to mlxsw_core_port_init()

Obtain HW id and pass it down to mlxsw_core_port_init() as it would be
used as switch_id in devlink and exposed to user.

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