Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - bifrost: scripts: bifrost-provision.sh: Set defaults for Ironic variables

    When running the bifrost jobs for the OPNFV 3rd Party CI, the Ironic
    variables are not defined and we get the following error:

    ./scripts/bifrost-provision.sh: line 112: BIFROST_IRONIC_INSPECTOR_VERSION: unbound variable

    As such, we need to provide reasonable defaults when we are running this
    script outside of XCI.

    Change-Id: I9cc3ae1b70494637a85558b9cae99fc1eeaebc74
    Signed-off-by: Markos Chandras <mchandras@suse.de>