Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Fix the config of vping net

    Change-Id: I71cea850985c67cf4c4e42a29600f9d63291fc94
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index ad44bfd..5f18bc3 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit ad44bfd97555a7372269db539857fd53fffb0460
+Subproject commit 5f18bc39015c906767b27596a0db6e7077500ff1