Update git submodules

Update git submodules

* Update docs/submodules/armband from branch 'stable/danube'
  - bootstrap, dea_base, nailgun: Pin 4.8.0-43 kernel

    Since newer kernels have issues with AAVMF + vhost_net,
    we need to also temporarily blacklist vhost_net.

    NOTE: This change also adds linux-image-extra packages to both x86_64
          and AArch64 target image(s).

    TODO: Remove vhost_net blacklist (later).

    JIRA: ARMBAND-161
    JIRA: ARMBAND-171
    JIRA: ARMBAND-227
    JIRA: ARMBAND-230
    JIRA: ARMBAND-239
    JIRA: ARMBAND-244

    Change-Id: I456f4235d04375905df9d6f776b84f2e0eee22d6
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 8f772f7e9d9d3e41575e3f7010a1717d3b6894ae)