net: phy: qca807x: Support SFP through phy_port interface

net: phy: qca807x: Support SFP through phy_port interface

QCA8072/8075 may be used as combo-port PHYs, with Serdes (100/1000BaseX)
 and Copper interfaces. The PHY has the ability to read the configuration
it's in.  If the configuration indicates the PHY is in combo mode, allow
registering up to 2 ports.

Register a dedicated set of port ops to handle the serdes port, and rely
on generic phylib SFP support for the SFP handling.

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/20260108080041.553250-13-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>