Merge branch 'net-phy-rework-linkmodes-handling-in-a-dedicated-file'

Maxime Chevallier says:

====================
net: phy: Rework linkmodes handling in a dedicated file

This is V5 of the phy_caps series. In a nutshell, this series reworks the way
we maintain the list of speed/duplex capablities for each linkmode so that we
no longer have multiple definition of these associations.

That will help making sure that when people add new linkmodes in
include/uapi/linux/ethtool.h, they don't have to update phylib and phylink as
well, making the process more straightforward and less error-prone.

It also generalises the phy_caps interface to be able to lookup linkmodes
from phy_interface_t, which is needed for the multi-port work I've been working
on for a while.

This V5 addresse Russell's and Paolo's reviews, namely :

 - Error out when encountering an unknown SPEED_XXX setting

   It prints an error and fails to initialize phylib. I've tested by
   introducing a dummy 1.6T speed, I guess it's only a matter of time
   before that actually happens :)

 - Deal more gracefully with the fixed-link settings, keeping some level of
   compatibility with what we had before by making sure we report a
   single BaseT mode like before.

V1 : https://lore.kernel.org/netdev/20250222142727.894124-1-maxime.chevallier@bootlin.com/
V2 : https://lore.kernel.org/netdev/20250226100929.1646454-1-maxime.chevallier@bootlin.com/
V3 : https://lore.kernel.org/netdev/20250228145540.2209551-1-maxime.chevallier@bootlin.com/
V4 : https://lore.kernel.org/netdev/20250303090321.805785-1-maxime.chevallier@bootlin.com/
====================

Link: https://patch.msgid.link/20250307173611.129125-1-maxime.chevallier@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>