police: add support for packet-per-second rate limiting

police: add support for packet-per-second rate limiting

Allow a policer action to enforce a rate-limit based on packets-per-second,
configurable using a packet-per-second rate and burst parameters.

e.g.
 # $TC actions add action police pkts_rate 1000 pkts_burst 200 index 1
 # $TC actions ls action police
 total acts 1

	action order 0:  police 0x1 rate 0bit burst 0b mtu 4096Mb pkts_rate 1000 pkts_burst 200
	ref 1 bind 0

Signed-off-by: Baowen Zheng <baowen.zheng@corigine.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Louis Peens <louis.peens@netronome.com>
Signed-off-by: David Ahern <dsahern@kernel.org>