Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Switch to vmtp commit id

    The patch "Reuse the router passed as config if available" [1] was
    merged.

    [1] https://review.openstack.org/#/c/588459/

    Change-Id: Iad8a1ff694f0bff3e13922a6c248dbe49b313a11
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index ddf3051..5ece152 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit ddf30512b98745460c1d162a54a18b0a8a814912
+Subproject commit 5ece1528f52fc9b759e103e40375f40db1abc4b5