Merge branch 'Add-MT7629-ethernet-support'

Sean Wang says:

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Add MT7629 ethernet support

MT7629 inlcudes two sets of SGMIIs used for external switch or PHY, and embedded
switch (ESW) via GDM1, GePHY via GMAC2, so add several patches in the series to
make the code base common with the old SoCs.

The patch 1, 3 and 6, adds extension for SGMII to have the hardware configured
for 1G, 2.5G and AN to fit the capability of the target PHY. In patch 6 could be
an example showing how to use these configurations for underlying PHY speed to
match up the link speed of the target PHY.

The patch 4 is used for automatically configured the hardware path from GMACx to
the target PHY by the description in deviceetree topology to determine the
proper value for the corresponding MUX.

The patch 2 and 5 is for the update for MT7629 including dt-binding document and
its driver.
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Signed-off-by: David S. Miller <davem@davemloft.net>