Update git submodules

Update git submodules

* Update docs/submodules/pharos from branch 'stable/euphrates'
  - Merge "[fuel] Use PXE interface index from net_config" into stable/euphrates
  - [fuel] Use PXE interface index from net_config

    Instead of assuming the PXE network interface is always the first,
    read its index from 'net_config' section.

    Change-Id: I0b4e9fc89297f4bd718a2e5336746917347c89e1
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 30ce269378cefdd14377c838687c4052d8c7e55d)