Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "Drop Ironic DB using non-default password"
  - Drop Ironic DB using non-default password

    The current implementation relays on the fact that the existing mysql
    deployment the root user can remove has access to the root user
    without its password. It's possible to drop the Ironic database using
    the same credentials that were used during its creation.

    Change-Id: I4b26455e06e5f024d2bd8c42065367838bb4aa0f
    Signed-off-by: Victor Morales <victor.morales@intel.com>