net: mvpp2: update PCS driver to use neg_mode

Update mvpp2's embedded PCS drivers to use neg_mode rather than the
mode argument, remembering to update the ACPI path as well. As there
are no pcs_link_up() methods, this only affects the two pcs_config()
methods.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/E1qA8EJ-00EaFx-P6@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>