mlxsw: reg: Add ptps field in QoS ETS Element Configuration Register

The PTP Shaper field is used for enabling and disabling of port-rate based
shaper which is slightly lower than port rate.

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>