Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Clean redundant error logs of refstack_defcore in the console"
  - Clean redundant error logs of refstack_defcore in the console

    1. Remove the file "refstack-error.log", and all the stderr and stdout
    will be stored in refstack.log
    2. Clean redundant error logs in the console and all the detailed error
    logs will be found in refstack.log.

    Change-Id: I7e71567c98dc89c529421eccbf1b497962b07405
    Signed-off-by: Linda Wang <wangwulin@huawei.com>