Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "scapy: Fix conflict of scapy libraries"
  - scapy: Fix conflict of scapy libraries

    T-Rex requires a modified version of SCAPY library for python3
    to function properly. It doesn't work with vanilla version of
    scapy-python3 module, which is installed within vsperf environment by
    pip for Xena. Currently vanilla scapy is imported by Xena and
    enforced to T-Rex too, which causes following issues:

    * missing implementation of Dot1AD causes failures
    * broken multistream feature in T-Rex

    VSPERF loads all Traffic Generator classes and thus all
    imports performed at module level are performed. The solution
    would be to import SCAPY module by Xena only in case, that Xena
    traffic generator is really used. Please see JIRA for additional
    information.

    JIRA: VSPERF-566

    Change-Id: I8018bc0126e752cc9f966252d17dadb6a5554b37
    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>