Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Leverage to Xtesting 0.51

    It removes ci_loop which has been useless from Docker slicing.
    It can filter now on any env var (e.g. CI_LOOP if required by XCI).

    Change-Id: Ibd685edf4636bd251c85466e8b4febcd1e20d312
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 06b9ace..cb33fa1 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 06b9ace7a0333d723972502ab3ce5784b6cba689
+Subproject commit cb33fa13d1a58dfa52b218e4e5aaf6cfa09b0cae