Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "ixia: Fix VLAN support by IxNet class"
  - ixia: Fix VLAN support by IxNet class

    IxNet class, which controls IXIA via IxNetwork TCL
    server, did not support VLAN configuration. Main TCL
    script 3rd_party/ixia/ixnetrfc2544.tcl was updated
    to support VLAN configuration.

    JIRA: VSPERF-499

    Change-Id: I89b33dfc653fd59c2983e78a6532812a4c29bddf
    Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
    Reviewed-by: Al Morton <acmorton@att.com>
    Reviewed-by: Christian Trautman <ctrautma@redhat.com>
    Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
    Reviewed-by: Trevor Cooper <trevor.cooper@intel.com>