mlxsw: reg: Extend QPCR register

The QoS Policer Configuration Register (QPCR) is used to configure
hardware policers. Extend this register with following fields and
defines which will be used by subsequent patches:

1. Violate counter: reads number of packets dropped by the policer
2. Clear counter: to ensure we start counting from 0
3. Rate and burst size limits

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>