net: phy: phy_port: Correctly recompute the port's linkmodes

net: phy: phy_port: Correctly recompute the port's linkmodes

a PHY-driven phy_port contains a 'supported' field containing the
linkmodes available on this port. This is populated based on :
 - The PHY's reported features
 - The DT representation of the connector
 - The PHY's attach_mdi() callback

As these different attrbution methods work in conjunction, the helper
phy_port_update_supported() recomputes the final 'supported' value based
on the populated mediums, linkmodes and pairs.

However this recompute wasn't correctly implemented, and added more
modes than necessary by or'ing the medium-specific modes to the existing
support. Let's fix this and properly filter the modes.

Fixes: 589e934d2735 ("net: phy: Introduce PHY ports representation")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Link: https://patch.msgid.link/20260205092317.755906-4-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>