LAG upgrade - 16: optimizing standard extended LAG member port entries

Updated #standard #extended #member #port agent mapper routines in LAG module. The agent #iterator routines and #mapper #routine has been updated to use standard member port entry based #indexing. This will access the port entries by using the #native #indexing. This removes references to the standard member port statistics indexing used earlier. The extended entries add support for #attributes like #custom #destination #address for the #LACP control and marker #PDUs, these will #default to the standard #Slow_Protocols_Multicast address.

#LAG update 24 ...
[commit aed9770ef28ed6939f60c5a24ada0f62878ee613] (https://github.com/nes-repo/NES-Open-Switch/commit/aed9770ef28ed6939f60c5a24ada0f62878ee613)