Description of problem:
ovs_extra option for ovs-dpdk-bond is extended twice.
Due to that, the same command executed to OVS DPDK bond twice.
This duplication is unnecessary. We should remove it.

Version-Release number of selected component (if applicable):
OSP17.1

How reproducible:
Always when os-net-config runs.

Steps to Reproduce:
1. Set ovs_extra for OVS DPDK Bond like below.
~~~
  members:
  - type: ovs_dpdk_bond
    name: dpdkbond-tenant1
    ovs_extra:
    - set interface dpdkbond-tenant1-port0 options:dpdk-lsc-interrupt=true
    - set interface dpdkbond-tenant1-port1 options:dpdk-lsc-interrupt=true
~~~
2. Run os-net-config with verbose mode.
3.

Actual results:
The command assigned at ovs_extra executed twice per line.

Expected results:
THe command assigned at ovs_extra executed once per line.

Additional info:
This behavior seems to come from the following implementation.

- os_net_config/impl_ifcfg.py

~~~
    626         elif isinstance(base_opt, objects.OvsDpdkBond):
    627             ovs_extra.extend(base_opt.ovs_extra)
    628             # Referring to bug:1643026, the below commenting of the interfaces,
    629             # is to workaround the error, but is not the long term solution.
    630             # The long term solution is to run DPDK options before
    631             # os-net-config, which is being tracked at BUG:1654975
    632             # if base_opt.primary_interface_name:
    633             #    primary_name = base_opt.primary_interface_name
    634             #    self.bond_primary_ifaces[base_opt.name] = primary_name
    635             data += "DEVICETYPE=ovs\n"
    636             data += "TYPE=OVSDPDKBond\n"
    637             data += "OVS_BRIDGE=%s\n" % base_opt.bridge_name
    638             if base_opt.members:
    639                 for bond_member in base_opt.members:
    640                     # Validation of DPDK port having only one interface is done
    641                     # prior to this. So accesing the interface name statically.
    642                     # Also dpdk_devargs would be valid here, since
    643                     # bind_dpdk_interfaces () is invoked before this.
    644                     dpdk_devargs = utils.get_dpdk_devargs(
    645                         bond_member.members[0].name, self.noop)
    646                     ovs_extra.append("set Interface %s options:"
    647                                      "dpdk-devargs=%s"
    648                                      % (bond_member.name, dpdk_devargs))
    649                 members = [member.name for member in base_opt.members]
    650                 data += ("BOND_IFACES=\"%s\"\n" % " ".join(members))
    651                 # MTU configuration given for the OvsDpdkbond shall be applied
    652                 # to each of the members of the OvsDpdkbond
    653                 if base_opt.mtu:
    654                     for member in base_opt.members:
    655                         ovs_extra.append("set Interface %s mtu_request=$MTU" %
    656                                          member.name)
    657                 if base_opt.rx_queue:
    658                     data += "RX_QUEUE=%i\n" % base_opt.rx_queue
    659                     for member in base_opt.members:
    660                         ovs_extra.append("set Interface %s options:n_rxq="
    661                                          "$RX_QUEUE" % member.name)
    662             if base_opt.ovs_options:
    663                 data += "OVS_OPTIONS=\"%s\"\n" % base_opt.ovs_options
    664             ovs_extra.extend(base_opt.ovs_extra)
~~~
At line 627 and 664 runs ovs_extra.extend(base_opt.ovs_extra).
This creates the duplicated entries.