Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Ensure the ssh config files are created per distro

    If 2 jobs for different distros start on the same host, the
    generated xci-vm-config files might be rewritten by both jobs
    causing trouble for the other. This change creates ssh config
    per distro to prevent potential issues.

    Change-Id: If6c0a86fd51bf3ba920e9206849ed1537894c7e1
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>