Update git submodules

Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Update all existing test specifications

    1. Update the names of 2 vping test cases
    2. Update the names of 8 ha test cases
    3. Update the sub test cases within osinterop 2017.09
    4. Split IPv6 into ipv6_api and ipv6_scenario
    5. Update the names of sdnvpn test cases
    6. Update the names of 4 tempest scenario test cases
    7. Remove forwardingpackets

    JIRA: DOVETAIL-685

    Change-Id: I0d91b8a0477576e18581eb2788fdb666063c89b7
    Signed-off-by: xudan <xudan16@huawei.com>