Merge branch 'pcs-xpcs-stmmac-add-1000BASE-X-AN-for-network-switch'

Merge branch 'pcs-xpcs-stmmac-add-1000BASE-X-AN-for-network-switch'

Ong Boon Leong says:

====================
pcs-xpcs, stmmac: add 1000BASE-X AN for network switch

Thanks for v4 review feedback in [1] and [2]. I have changed the v5
implementation as follow.

v5 changes:
1/5 - No change from v4.
2/5 - No change from v4.
3/5 - [Fix] make xpcs_modify_changed() static and use
      mdiodev_modify_changed() for cleaner code as suggested by
      Russell King.
4/5 - [Fix] Use fwnode_get_phy_mode() as recommended by Andrew Lunn.
5/5 - [Fix] Make fwnode = of_fwnode_handle(priv->plat->phylink_node)
      order after priv = netdev_priv(dev).

v4 changes:
1/5 - Squash v3:1/7 & 2/7 patches into v4:1/6 so that it passes build.
2/5 - [No change] same as v3:3/7
3/5 - [Fix] Fix issues identified by Russell in [1]
4/5 - [Fix] Drop v3:5/7 patch per input by Russell in [2] and make
            dwmac-intel clear the ovr_an_inband flag if fixed-link
            is used in ACPI _DSD.
5/5 - [No change] same as v3:7/7

For the steps to setup ACPI _DSD and checking, they are the same
as in [3]

Reference:
[1] https://patchwork.kernel.org/comment/24894239/
[2] https://patchwork.kernel.org/comment/24895330/
[3] https://patchwork.kernel.org/project/netdevbpf/cover/20220610033610.114084-1-boon.leong.ong@intel.com/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>