Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Add BRANCH as Docker build arg

    It conforms with the prerequisite of the current releng Docker script.
    BRANCH can be considered as useless because releng already clones the
    right git branch.

    It's a temporarily solution before modifying a script used by lots of
    OPNFV projects.

    Change-Id: I585d7a79a9ebaeaffd69af1da1731c44e131f6b5
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 67557f7..9e72ad1 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 67557f7cbd0e96b1654d9925bc163cb46c25d0c9
+Subproject commit 9e72ad1edd88aada55a0328cd72d4941c4e6fc60