Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "xci: scripts: vm: Install additional packages to clean VM"
  - xci: scripts: vm: Install additional packages to clean VM

    Install some additional packages to the clean VM which can be useful
    during debugging. Moreover, we move the common distribution packages
    into a variable in order to simplify the code a little bit.

    Change-Id: I0405820900a15fec730a2bbfc95a1d1f3485bf0f
    Signed-off-by: Markos Chandras <mchandras@suse.de>