Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Update repo archive script to handle empty repos"
  - Update repo archive script to handle empty repos

    After an empty repo is cloned, and we attempt to pull in changes, git
    fails due to not know which branch to pull from. Explicitily pulling
    from origin into master should resolve this.

    Change-Id: I6bed85779c1bb571559c263800e8ea55ece3aa62
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>