Policer: Overhead adjustment at interface level

Policer-overhead adjustment for ingress and egress policers is defined on a per IFL/direction granularity in order to address MEF CE 2.0 requirements to the bandwidth profile. The policer-overhead adjustment is the range of -16 bytes to +16 bytes. It is applied for all the policers that take into account L1/L2 packet length that are exercised in the specified IFL/direction, including corresponding IFF feature policers, and is applied only to interface/filter-based policers.