Update git submodules

Update git submodules

* Update docs/submodules/armband from branch 'stable/euphrates'
  - p/fuel: bm: linux-image-generic-hwe-16.04-edge

    The Salt way to pin the kernel version is via its reclass model, by
    defining system.kernel.version. However, this only works with
    explicit kernel package names and not with meta package names
    (e.g. linux-image-4.13.0-9916-generic is expected instead of
          linux-image-generic-hwe-16.04-edge, which would break the
    `linux_kernel_old_absent` state).

    For now, let's explicitly call `pkg.install` for the kernel and
    headers packages, using the meta package name to ensure automatic
    fallback to Ubuntu packages if Armband repos are missing,
    respectively to automatically pick up new kernel package names
    in case of meta + kernel packages bump later.

    JIRA: ARMBAND-280

    Change-Id: I5448df1de1b3c211583708402b5c7497df92fc16
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 67aed7515601fc8b4d2dea326c4e634de7f8fa48)