Merge branch 'remove-some-unused-phylink-legacy'

Russell King says:

====================
Remove some unused phylink legacy

I believe we are now in a position where some of the legacy phylink code
can be removed!

I believe that all DSA drivers do not make use of any pre-March 2020
phylink behaviour - all drivers now seem to set legacy_pre_march2020 to
false, and the conditions that DSA sets it to true are no longer
satisifed by any driver.

Moreover, no one uses the .mac_an_restart() method, so this can also be
removed.
====================

Link: https://lore.kernel.org/r/ZLERQ2OBrv44Ppyc@shell.armlinux.org.uk
Signed-off-by: Paolo Abeni <pabeni@redhat.com>