Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Omit functional tests from coverage report analysis"
  - Omit functional tests from coverage report analysis

    Coverage report will also search for new code introduced in
    /yardstick/tests/functional. Any modification in functional
    test cases must be omitted from coverage report.

    JIRA: YARDSTICK-1308

    Change-Id: Ib9c48102340f70d8d79f78dc81cbfe7b29c81115
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>