mlxsw: spectrum_ptp: Add PTP initialization / finalization for Spectrum-2

mlxsw: spectrum_ptp: Add PTP initialization / finalization for Spectrum-2

Lay the groundwork for Spectrum-2 support. On Spectrum-2, the packets get
the time stamps from the CQE, which means that the time stamp is attached
to its packet.

Configure MTPTPT to set which message types should arrive under which
PTP trap. PTP0 will be used for event message types, which means that
the packets require time stamp. PTP1 will be used for other packets.

Note that in Spectrum-2, all packets contain time stamp by default. The two
types of traps (PTP0, PTP1) will be used to separate between PTP_EVENT
traps and PTP_GENERAL traps, so then the driver will fill the time stamp as
part of the SKB only for event message types.

Later the driver will enable the traps using 'MTPCPC.ptp_trap_en' bit.
Then, PTP packets start arriving through the PTP traps.

Currently, the structure 'mlxsw_sp2_ptp_state' contains only the common
structure, the next patches will extend it.

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>