net: dsa: b53: do not set learning and unicast/multicast on up

net: dsa: b53: do not set learning and unicast/multicast on up

When a port gets set up, b53 disables learning and enables the port for
flooding. This can undo any bridge configuration on the port.

E.g. the following flow would disable learning on a port:

$ ip link add br0 type bridge
$ ip link set sw1p1 master br0 <- enables learning for sw1p1
$ ip link set br0 up
$ ip link set sw1p1 up <- disables learning again

Fix this by populating dsa_switch_ops::port_setup(), and set up initial
config there.

Fixes: f9b3827ee66c ("net: dsa: b53: Support setting learning on port")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20250429201710.330937-12-jonas.gorski@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>