Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - xci: Fix the Gerrit Trigger clone issue for external scenarios

    When a patch comes in for an external scenario, Gerrit Trigger injects
    refs for that patch for the corresponding project. With the previous
    configuration, job attempts to get that patch for releng-xci instead
    of the actual project.

    But switching to the right project causes Jenkins jobs to fail since
    the releng-xci will not be checked out to WORKSPACE.

    This change makes the clone for the repo/patch work and then it wipes
    out the WORKSPACE and clones releng-xci there to get the actual script
    parts to work.

    Change-Id: Ide31c21a209dff953118f51e9b09de1d206a3085
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>