Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Bugfix: openstack router list broken in Yardstick container - dovetail" into stable/fraser
  - Bugfix: openstack router list broken in Yardstick container - dovetail

    Dependancy of python-openstackclient is not constrained.
    This patch specify openstacksdk and openstackclient's version according to [1].

    This patch apply for bugfix and need to backported to fraser stable branch.
    Continual work need to be done in Gambia according to YARDSTICK-1398.

    [1]
    https://github.com/openstack/requirements/blob/stable/pike/upper-constraints.txt

    JIRA: DOVETAIL-728

    Change-Id: I57c718e192699ac322150458d18508b06c93d22b
    Signed-off-by: rexlee8776 <limingjiang@huawei.com>
    (cherry picked from commit 1e53af56c278921dad5671a5c4b8cafcdaa54ba9)
    Signed-off-by: rexlee8776 <limingjiang@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 297bfc5..86b9b27 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 297bfc5f20f5b0077968870c2270dcf1b8114724
+Subproject commit 86b9b2780ce661a56bd3f25312eedceab3aa39e0