net: fec: remove unused members from struct fec_enet_private

net: fec: remove unused members from struct fec_enet_private

Three members of struct fec_enet_private have not been used since
they were first introduced into the FEC driver (commit 6605b730c061
("FEC: Add time stamping code and a PTP hardware clock")). Namely,
last_overflow_check, rx_hwtstamp_filter and base_incval. These
unused members make the struct fec_enet_private a bit messy and
might confuse the readers. There is no reason to keep them in the
FEC driver any longer.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://lore.kernel.org/r/20230718090928.2654347-4-wei.fang@nxp.com
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>