Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "Trex_2544_verification: Add verification functionality to Trex code"
  - Trex_2544_verification: Add verification functionality to Trex code

    - Adds T-Rex verification step as implemented by other trafficgens
    - Adds check in rfc2544 loop for if no packets are received to fail test
      immediately
    - Refactors the trial code to support the verification option
    - Adds trial_run function
    - Removed unused line speed configuration setting

    JIRA: VSPERF-553

    Change-Id: Ie324fe8fb6bf79fe0dc337b91af2bf83e901a8ab
    Signed-off-by: Christian Trautman <ctrautma@redhat.com>