RTL838X SerDes is now completely managed by the PCS driver so it's time
to remove all the unused leftovers from DSA and PHY drivers to have that
finally separated.
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/20876
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>