Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "Install xz utility on deployment host"
  - Install xz utility on deployment host

    Functest Smoke test requires additional images to be available
    during testing. One of the images is decompressed using xz and we
    need this to be available on deployment host in order to be able
    to have the images available for Functest execution.

    Change-Id: I5647b3bef37fc55e8c5cc9aec5d0b2c3ea628b8a
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>