Merge branch 'net-pcs-stmmac=add-C37-AN-SGMII-support'

Ong Boon Leong says:

====================
net: pcs, stmmac: add C37 AN SGMII support

This patch series adds MAC-side SGMII support to stmmac driver and it is
changed as follow:-

1/6: Refactor the current C73 implementation in pcs-xpcs to prepare for
     adding C37 AN later.
2/6: Add MAC-side SGMII C37 AN support to pcs-xpcs
3,4/6: make phylink_parse_mode() to work for non-DT platform so that
       we can use stmmac platform_data to set it.
5/6: Make stmmac_open() to only skip PHY init if C73 is used, otherwise
     C37 AN will need phydev to be connected to phylink.
6/6: Finally, add pcs-xpcs SGMII interface support to Intel mGbE
     controller.

The patch series have been tested on EHL CRB PCH TSN (eth2) controller
that has Marvell 88E1512 PHY attached over SGMII interface and the
iterative tests of speed change (AN) + ping test have been successful.

[63446.009295] intel-eth-pci 0000:00:1e.4 eth2: Link is Down
[63449.986365] intel-eth-pci 0000:00:1e.4 eth2: Link is Up - 1Gbps/Full - flow control off
[63449.987625] IPv6: ADDRCONF(NETDEV_CHANGE): eth2: link becomes ready
[63451.248064] intel-eth-pci 0000:00:1e.4 eth2: Link is Down
[63454.082366] intel-eth-pci 0000:00:1e.4 eth2: Link is Up - 100Mbps/Full - flow control off
[63454.083650] IPv6: ADDRCONF(NETDEV_CHANGE): eth2: link becomes ready
[63456.465179] intel-eth-pci 0000:00:1e.4 eth2: Link is Down
[63459.202367] intel-eth-pci 0000:00:1e.4 eth2: Link is Up - 10Mbps/Full - flow control off
[63459.203639] IPv6: ADDRCONF(NETDEV_CHANGE): eth2: link becomes ready
[63460.882832] intel-eth-pci 0000:00:1e.4 eth2: Link is Down
[63464.322366] intel-eth-pci 0000:00:1e.4 eth2: Link is Up - 1Gbps/Full - flow control off
====================

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