net: mdio: mdiobus_register: update validation test
Now that C45 uses its own read/write methods, the validation performed
when a bus is registers needs updating. All combinations of C22 and
C45 are supported, but both read and write methods must be provided,
read only busses are not supported etc.
Signed-off-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Michael Walle <michael@walle.cc> Signed-off-by: Jakub Kicinski <kuba@kernel.org>