Update ECMP hash table update for keys used

[5abeel]

The P4Compiler has changed the generated key names in p4info.txt for ECMP hash tables (the table types have changed in LNWv3 to WCM table). Due to the change, retrieving this table was resulting in an infrap4d crash.

Generated table keys are shown below:

tables {
  preamble {
    id: 49661222
    name: "linux_networking_control.ecmp_hash_table"
    alias: "ecmp_hash_table"
  }
  match_fields {
    id: 1
    name: "flex" ## --> this should be matched in our code
    bitwidth: 16
    match_type: TERNARY
  }
  match_fields {
    id: 2
    name: "hash" ## --> this should be matched in our code
    bitwidth: 3
    match_type: TERNARY
  }

Also, in LNWv3, we do not have the zero_padding, so commenting the section out for ecmp_hash_table

[ffoulkes]

LGTM

[vsureshkumarp]

Changes looks good to me.