Update git submodules

* Update docs/submodules/yardstick from branch 'stable/danube'
  - Bugfix: fix HA test case tc046

    The original way to kill keystone service didn't work anymore.
    this patch uses killall -u to kill keystone processes.

    Change-Id: I553b716f17a5ab7e57630468517642a92f06dd27
    Signed-off-by: JingLu5 <lvjing5@huawei.com>
    (cherry picked from commit 909606466c50aab19017b6e6cedd3e213aff7c27)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index edfaab0..09c0361 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit edfaab003e182b500b88adbac94625e9053455fb
+Subproject commit 09c03612744836061af590c724de26793f88b38f