Merge branch 'phy-c45-loopback'

Wong Vee Khee says:

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Add support for Clause-45 PHY Loopback

This patch series add support for Clause-45 PHY loopback.

It involves adding a generic API in the PHY framework, which can be
accessed by all C45 PHY drivers using the .set_loopback callback.

Also, enable PHY loopback for the Marvell 88x3310/88x2110 driver.
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Signed-off-by: David S. Miller <davem@davemloft.net>