realtek: pcs: drop legacy comment and warning

realtek: pcs: drop legacy comment and warning

We finally reached the point where PCS has full control over SerDes and
no parts of this are scattered in other drivers anymore. To make that
clear, drop the comment in pcs_config that explains this former state
and remove a warning which states that pcs_config isn't fully
implemented yet.

Add a generic output to at least keep a generic sign of life from the
PCS driver, independently from what the variant-specific code currently
prints.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/21481
Signed-off-by: Robert Marko <robimarko@gmail.com>