net: phy: Keep track of EEE configuration

Have phylib keep track of the EEE configuration. This simplifies the
MAC drivers, in that they don't need to store it.

Future patches to phylib will also make use of this information to
further simplify the MAC drivers.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20240302195306.3207716-4-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>