net: phy: realtek: fix double page ops in generic Realtek driver

When adding missing callbacks I missed that one had them set already.
Interesting that the compiler didn't complain.

Fixes: daf3ddbe ("net: phy: realtek: add missing page operations")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>