Update git submodules

Update git submodules

* Update docs/submodules/armband from branch 'master'
  - salt: virt: Extend libvirt_domain

    Extend salt virt modelling capabilities with support for:
    - hw_firmware_type;
    - virt_machine_model;
    - cpu_model;

    This requires extending/patching:
    - libvirt_domain.jinja template (part of salt package, handled via
      armband.libvirt_domain_template new state);
    - _modules/virtng.py custom module;
    - salt/control/virt.sls;

    The new support is leveraged via our reclass model with AArch64
    specific values.

    Change-Id: I34bdb235cb7765ecdde365761dbd2c942f699039
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>