Update git submodules

* Update docs/submodules/releng from branch 'master'
  - jjb: xci: Use the correct SSH configuration file

    We need to use the XCI specific SSH configuration file so rsync can
    tranfer the working directory to the virtual machine. This also
    drop the ironic command like we do in the XCI jobs.

    Change-Id: I10ce38db6777d5dbfbe62961c88b3902de2160e2
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index c7fdb45..ef537c1 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit c7fdb455dcc51b5d56261f12b4169e899554139b
+Subproject commit ef537c1ebf7a46b884abb82f1e6a54483f07b93b