Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Raise exceptions when SDN_CONTROLLER_IP is None"
  - Raise exceptions when SDN_CONTROLLER_IP is None

    Change-Id: Ia0d00a6b3c4c4936dc10602e838f507beea0c592
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 0018213..53cd7f8 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 00182139afbfa67541340d46e49d948d1f69840c
+Subproject commit 53cd7f8176c996014decb7311d9f546f6b8f2497