E825C products feature a new PHY model - ETH56G.

Introduces all necessary PHY definitions, functions etc. for ETH56G PHY,
analogous to E82X and E810 ones with addition of a few HW-specific
functionalities for ETH56G like one-step timestamping.

It ensures correct PTP initialization and operation for E825C products.
Co-developed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Co-developed-by: Michal Michalik <michal.michalik@intel.com>
Signed-off-by: Michal Michalik <michal.michalik@intel.com>
Signed-off-by: Sergey Temerkhanov <sergey.temerkhanov@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Co-developed-by: Karol Kolacinski <karol.kolacinski@intel.com>
Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20240528-next-2024-05-28-ptp-refactors-v1-7-c082739bb6f6@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>