Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Fix CLI argument handling in nsb_setup.sh

    CLI argument $1 was used for both admin-openrc file with OpenStack
    credentials and Yardstick Docker image, so obviously one of them would
    be wrong, and NSB setup would fail at some point.

    Historically, admin-openrc could be supplied as CLI argument $1, but
    change https://gerrit.opnfv.org/gerrit/56493 broke it, which means
    specifying Yardstick Docker image as CLI argument never worked.

    This fix implements support for the following CLI options:
      -o openrc     Specify admin-openrc file with OpenStack credentials
      -i image      Specify Yardstick Docker image
      -h            Provide usage information

    For backward compatibility reasons, admin-openrc file can be supplied
    either with the -o option, or as a CLI argument.

    JIRA: YARDSTICK-1137

    Change-Id: I3e9904970560468c24b21738203bc67b7591f9e4
    Signed-off-by: Patrice Buriez <patrice.buriez@intel.com>