Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge changes from topics 'YARDSTICK-1343', 'YARDSTICK-1342'

    * changes:
      Cleanup EnvironmentTestCase unit tests
      Cleanup Testcase unit tests

  - Cleanup EnvironmentTestCase unit tests

    Removed unneeded output.

    JIRA: YARDSTICK-1343

    Change-Id: Ifad21a62ce1152976952a4b8c5a142fa5a544904
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
  - Cleanup Testcase unit tests

    Removed unneeded output.

    JIRA: YARDSTICK-1342

    Change-Id: I45ab14f854cd059625c1a96959b1cbd0a19f52a8
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>