net: fec: convert to ndo_hwtstamp_get() and ndo_hwtstamp_set()

The hardware timestamping through ndo_eth_ioctl() is going away.
Convert the FEC driver to the new API before that can be removed.

After removing the timestamping logic from fec_enet_ioctl(), the rest
is equivalent to phy_do_ioctl_running().

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Wei Fang <wei.fang@nxp.com>
Link: https://lore.kernel.org/r/20230801142824.1772134-7-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>