Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Enable sdnvpn testcase for F-release

    sdnvpn conforms with OpenStack Pike requirements then it could be
    enabled in functest-features and functest-restapi (master) [1].

    [1] https://gerrit.opnfv.org/gerrit/#/c/47277/

    Change-Id: Iedcb645d897684f169e4cf536838bf1f0951b6d9
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 11c2123..587f916 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 11c21239ace9bd45abf4e79bb52dc13f06ae43ee
+Subproject commit 587f9163769f988a8a3ba592dc10ef2d994588e8