Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "fuel, armband: Limit dovetail to Danube branch"
  - fuel, armband: Limit dovetail to Danube branch

    While at it, limit functest & yardstick to master and
    stable/euphrates, trying to work around missing job references
    in Danube scenarios on ZTE PODs.

    Change-Id: I89de0c3b3c914e1ad735980a995e5cae625238be
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index f555ded..2fa156f 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit f555dedcc0197e0fd08bbccff2aef72ebb8c0d68
+Subproject commit 2fa156fcf1a730e8e839ded5ebdd09dd0d31b94c