Update git submodules

* Update docs/submodules/releng from branch 'master'
  - fuel-deploy.sh: source local_env from securedlab

    While at it, revert BRIDGE default value to "pxebr" after recent
    Fuel rework was merged in [1].
    This mechanism will be leveraged by [2].

    Partially reverts commit: 68195fd

    [1] https://gerrit.opnfv.org/gerrit/#/c/38855/
    [2] https://gerrit.opnfv.org/gerrit/#/c/39521/

    Change-Id: Ic61487384029a7d16547a5035a1f1b34ecbea8d4
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 1df4517..55ffe9a 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 1df451788541046609e2bdda1b395b4109e8ca70
+Subproject commit 55ffe9aead06fc13b885c5dd04a170856c35b3c9