net: octeon: mgmt: convert to use ndo_hwtstamp callbacks

net: octeon: mgmt: convert to use ndo_hwtstamp callbacks

The driver implemented SIOCSHWTSTAMP ioctl command only. But it stores
timestamping configuration, so it is possible to report it to users.
Implement both ndo_hwtstamp_set and ndo_hwtstamp_get callbacks. After
this the ndo_eth_ioctl effectively becomes phy_do_ioctl - adjust
callback accordingly.

Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20251103150952.3538205-5-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>