Right now, the *_port_setup code is in dsa_switch_ops::port_enable(),
which is not the best place for it. This patch moves it to a more
suitable place, dsa_switch_ops::port_setup(), to match the function's
purpose and name.
This patch is a preparation for coming ACL support patch.
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>