Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - Merge "Update the way of running tempest"
  - Update the way of running tempest

    Use 'tempest run' instead of 'run_tempest.sh', which has
    been removed by tempest 16.0.0
    Also, 'tempest.py' has been renamed to 'run_tempest.py', to
    avoid package importing conflict

    Change-Id: I61e802e0381d1f33281610e98d05813c9b96faf9
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index b12c075..c2d2043 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit b12c075fc625d1f13e3864d11aba30650e0c96a6
+Subproject commit c2d2043fe34461b66011b974fc535f703e5fa2de