mlxsw: reg: Add Management Pulse Per Second Register

The MTPPS register provides the device PPS capabilities, configure the PPS
in and out modules and holds the PPS in time stamp.

Signed-off-by: Shalom Toledo <shalomt@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>