Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Add concurrency parameter to refstack_defcore tests"
  - Add concurrency parameter to refstack_defcore tests

    In fraser release we observed that refstack tests are executed in parallel
    and that might causes problems in CI because without concurrency
    parameter it will try to use as many cpus as possible and that might
    lead to race condition issues.

    This patch is created for backporting purposes to fraser branch
    where the problem occurs.

    JIRA: DOVETAIL-662

    Change-Id: I6cf0ad3a32e88f04abd00d69523aa8ac47c39470
    Signed-off-by: Dimitrios Markou <mardim@intracom-telecom.com>