net: mdio: cavium: Separate C22 and C45 transactions

The cavium IP can perform both C22 and C45 transfers.  Create separate
functions for each and register the C45 versions in both the octeon
and thunder bus driver.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>