Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Specify valid external network as an env"
  - Specify valid external network as an env

    In some deployments, the retrieved external network by the
    def get_external_net checked by "router:external" is not available.
    So it is necessary to specify the available external network
    as an env by user for some deployments.

    JIRA: FUNCTEST-865

    Change-Id: I561bc7d57e06214516a4cdbebd67632cd9746fba
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index cfd987a..f9fc2c1 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit cfd987a6ce153be88413a38ade2bea3af2f32dcd
+Subproject commit f9fc2c1df0c6293df3f7c5e413a8aab643a4177a