dsa: pass switch ID through devlink_port_attrs_set()

Pass the switch ID down the to devlink through devlink_port_attrs_set()
so it can be used by devlink_compat_switch_id_get(). Leave
ndo_get_port_parent_id implementation only for legacy.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>