net: phy: Only rely on phy_port for PHY-driven SFP

net: phy: Only rely on phy_port for PHY-driven SFP

Now that all PHY drivers that support downstream SFP have been converted
to phy_port serdes handling, we can make the generic PHY SFP handling
mandatory, thus making all phylib sfp helpers static.

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/20260108080041.553250-14-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>