Merge branch 'net-stmmac-improve-pcs-support'

Russell King says:

====================
net: stmmac: improve PCS support

This series is the next of the three part series sorting out the PCS
support in stmmac, building on part 2:

	net: stmmac: qcom-ethqos: further serdes reorganisation

Similar patches have been posted previously. This series does away with
the common SerDes PHY support, instead using a flag to indicate whether
2500Mbps mode is supported (STMMAC_FLAG_SERDES_SUPPORTS_2500M.) At this
time, I have no plans to resurect the common SerDes PHY support - the
generic PHY layer implementations are just too random to consider that,
and I certainly do not want the extra work of fixing that.

The reasoning here is that these patches should be safe to merge and
should not impact qcom-ethqos in any way.

We can then figure out how to work around qcom-ethqos hacks without
having to keep re-posting these same patches time and time again.
====================

Link: https://patch.msgid.link/abrNYVfZ1Iwff2EI@shell.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>