Even though the DWMAC driver uses some driver specific properties, the PHY
core has a bunch of generic properties and can deal with them nicely.

Let's deprecate our specific properties.

Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Rob Herring <robh@kernel.org>