Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 6b7dbd409be1181f6710935a3b8afc192900856d
  - Run Functest Benchmarking testcases in parallel

    Change-Id: If80365f10751fc18eefdff7a6b621de0b46276e4
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index d37ff06..6b7dbd4 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit d37ff067483aacb9b9549caf4d0a6d654be0cc94
+Subproject commit 6b7dbd409be1181f6710935a3b8afc192900856d