net: mdio: mdio-bitbang: Separate C22 and C45 transactions

The bitbbanging bus driver can perform both C22 and C45 transfers.
Create separate functions for each and register the C45 versions using
the new driver API calls.

The SH Ethernet driver places wrappers around these functions. In
order to not break boards which might be using C45, add similar
wrappers for C45 operations.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>