mlxsw: spectrum: Fix IP2ME CPU policer configuration

The CPU policer used to police packets being trapped via a local route
(IP2ME) was incorrectly configured to police based on bytes per second
instead of packets per second.

Change the policer to police based on packets per second and avoid
packet loss under certain circumstances.

Fixes: 9148e7cf ("mlxsw: spectrum: Add policers for trap groups")
Signed-off-by: Shalom Toledo <shalomt@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>