net: phy: broadcom: Add BCM54810 PHY entry

The BCM54810 PHY requires some semi-unique configuration, which results
in some additional configuration in addition to the standard config.
Also, some users of the BCM54810 require the PHY lanes to be swapped.
Since there is no way to detect this, add a device tree query to see if
it is applicable.

Inspired-by: Vikas Soni <vsoni@broadcom.com>
Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>