Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Replace assert statements in PipelineRules"
  - Replace assert statements in PipelineRules

    The class PipelineRules uses assert statements to check the correctness
    of an input parameter IP address. This commit will modify these lines
    to use a dedicated function "common.utils.make_ipv4_address".

    JIRA: YARDSTICK-966

    Change-Id: I1c4cc439a7716d36548125c87dfb0bc200714a56
    Signed-off-by: Miikka Koistinen <miikka.koistinen@nokia.com>