net: phy: marvell: Support SFP through phy_port interface

net: phy: marvell: Support SFP through phy_port interface

Convert the Marvell driver (especially the 88e1512 driver) to use the
phy_port interface to handle SFPs. This means registering a
.attach_port() handler to detect when a serdes line interface is used
(most likely, and SFP module).

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260108080041.553250-10-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>