Update git submodules

* Update docs/submodules/releng from branch 'master'
  to a7cfdcd27d0cc7f7b35ad18954c7a79ad959f982
  - Temporarily disable Xtesting MTS

    It will help debugging the log dump issues.

    Change-Id: I6c67d8372505f1980243daf26db1a2007697b7bb
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index e999c69..a7cfdcd 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit e999c69ef480272afe8ee91213bc13891e052082
+Subproject commit a7cfdcd27d0cc7f7b35ad18954c7a79ad959f982