net: enetc: add PTP synchronization support for ENETC v4

net: enetc: add PTP synchronization support for ENETC v4

Regarding PTP, ENETC v4 has some changes compared to ENETC v1 (LS1028A),
mainly as follows.

1. ENETC v4 uses a different PTP driver, so the way to get phc_index is
different from LS1028A. Therefore, enetc_get_ts_info() has been modified
appropriately to be compatible with ENETC v1 and v4.

2. The PMa_SINGLE_STEP register has changed in ENETC v4, not only the
register offset, but also some register fields. Therefore, two helper
functions are added, enetc_set_one_step_ts() for ENETC v1 and
enetc4_set_one_step_ts() for ENETC v4.

3. Since the generic helper functions from ptp_clock are used to get
the PHC index of the PTP clock, so FSL_ENETC_CORE depends on Kconfig
symbol "PTP_1588_CLOCK_OPTIONAL". But FSL_ENETC_CORE can only be
selected, so add the dependency to FSL_ENETC, FSL_ENETC_VF and
NXP_ENETC4. Perhaps the best approach would be to change FSL_ENETC_CORE
to a visible menu entry. Then make FSL_ENETC, FSL_ENETC_VF, and
NXP_ENETC4 depend on it, but this is not the goal of this patch, so this
may be changed in the future.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250829050615.1247468-14-wei.fang@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>