Update git submodules

* Update docs/submodules/releng from branch 'master'
  - jjb: xci: bifrost: Enable jobs and use XCI ssh configuration

    Enable the 'bifrost' jobs and also make use of the XCI specific
    ssh configuration file.

    Change-Id: I04d15610b596191622cf028b3408b4d63ee7090b
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index dfe4f90..2e39f53 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit dfe4f90bdcd765d3045ee1a9c6f00ea0b394e665
+Subproject commit 2e39f53a1c8d35f4f55361c0dcfb61ff327f60c3