mlxsw: spectrum_ptp: use PTP wide message type definitions

Use recently introduced PTP wide defines instead of a driver internal
enumeration.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Cc: Petr Machata <petrm@mellanox.com>
Cc: Jiri Pirko <jiri@nvidia.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>