net: ethtool: remove the duplicated handling from rxfh and rxnfc

Now that the handles have been separated - remove the RX Flow Hash
handling from rxnfc functions and vice versa.

Reviewed-by: Joe Damato <joe@dama.to>
Link: https://patch.msgid.link/20250611145949.2674086-3-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>