mlxsw: reg: Add QoS Policer Configuration Register

The QPCR register is used to create and control policers.
A policer can discard or change the color of packets that are
trapped by a specific trap.

Signed-off-by: Nogah Frankel <nogahf@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>