Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "scenario: Add AArch64 defaults"
  - scenario: Add AArch64 defaults

    Move scenario defaults.yml out of virtual/baremetal dirs, unifying
    them into a single, arch-specific defaults configuration file.

    Add AArch64 equivalent config, and arch-qualify default filename.
    For AArch64, bump VCPU number from 2 to 6.

    Change-Id: If9b39850af96e4c46e868b1d532bd301f9fd9f26
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>