Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "regression: OVS/DPDK regression tests"
  - regression: OVS/DPDK regression tests

    A set of regression tests for verification of OVS/DPDK
    features was introduced. Following features are tested:
    * DPDK NIC Support
    * DPDK Hotplug Support
    * RX Checksum Support
    * Flow Control Support
    * Multiqueue Support
    * Vhost User
    * Virtual Devices Support
    * NUMA Support
    * Jumbo Frame Support
    * Rate Limiting
    * Quality of Service

    JIRA: VSPERF-539

    Change-Id: I6c83e9c38e29f197a5236ac68c88d7045fef775b
    Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
    Signed-off-by: Martin Goldammer <martinx.goldammer@intel.com>
    Signed-off-by: Richard Elias <richardx.elias@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>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index e94899d..8a1b74a 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit e94899d6ce7a893dc77b46f33816735620d8e52a
+Subproject commit 8a1b74a4fdbafdef256cec64501f1ec751f03b9f