Drop several leftovers of SerDes configuration from PHY and DSA drivers.
Both drivers can be seen as free from any SoC-side SerDes stuff.
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/21360
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>