Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - SDNVPN-184: resources are not cleaned if tc fails

    * moved the cleanup code inside the finally block in each test case

    Change-Id: Ifc0fee58451923117c54040c716dad6827fbc7fa
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index e7693b7..6c878a2 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit e7693b748e16f6013b5dddf6eb5ebcf9d0bb0a3d
+Subproject commit 6c878a213164dc895841046170869a50e41c9e7a