Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 38c0e54ce5c354abd10035f2acb1204c057e4a8b
  - Conform with latest Functest backports

    New tempest plugins were backported to Jerma and Iruya.

    Change-Id: I1e8d4fef110609657d179aa978b2b4441200abde
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 75bc2f7..38c0e54 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 75bc2f7b75fe6047329058a3f49323fb07450a8d
+Subproject commit 38c0e54ce5c354abd10035f2acb1204c057e4a8b