Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 2ffba4a0e2ae6f7b8f99909e6d9149cfdda2a3bc
  - Fix slave in jjb-verify

    Change-Id: If84572168866f3b2a76db5d64304a0393e10d304
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 17e0e52..2ffba4a 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 17e0e520342dc7828e12d9792af1f5089ea3e458
+Subproject commit 2ffba4a0e2ae6f7b8f99909e6d9149cfdda2a3bc