Update git submodules

* Update docs/submodules/functest from branch 'stable/fraser'
  - Control vping cleanup step via --noclean

    Change-Id: Ic43b100348e77fd96aab9abc5a9ec4a0b47a2f87
    Signed-off-by: Linda Wang <wangwulin@huawei.com>
    (cherry picked from commit 1ca85485f74d09dfd6787b75fb40cb70dce64e4b)

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 4ca522b..4a68640 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 4ca522bdb4918bf97c0e2ad9b1c8c281c0133ffd
+Subproject commit 4a6864077a4989eb003efa1d18df2a78cb405155