Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Bugfix: ansible version should be the same both in Dockerfile and requirements.txt

    Because Dockerfile is using ansible script to install yardstick requirements.
    Or it may lead to exception when installing Yardstick.

    Change-Id: Ia83cf76675a7f3f1d0aa5c311e7b72be5c7ca5c3
    Signed-off-by: rexlee8776 <limingjiang@huawei.com>
    (cherry picked from commit 662de49b9f6c116d15882aed9e678cd3cf67494b)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 86b9b27..5fb2138 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 86b9b2780ce661a56bd3f25312eedceab3aa39e0
+Subproject commit 5fb2138dd163c83fa73e8766fc206d1c14409754