net: dsa/b53: use resolved link config in mac_link_up()

Convert the B53 driver to use the finalised link parameters in
mac_link_up() rather than the parameters in mac_config(). This is
just a matter of moving the call to b53_force_port_config().

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>