Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - ci: Add VPP test execution into CI daily job

    Basic set of VPP performance tests was added into
    OPNFV CI daily job.

    JIRA: VSPERF-509

    Change-Id: I9cd6086a958d67dd0e395f962111e6d2b44bf86c
    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>