Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Replace glance create image with shade client." into stable/fraser
  - Replace glance create image with shade client.

    Function create_image now uses shade client.

    JIRA: YARDSTICK-892

    Change-Id: Ia41d9ce702a1f24031080f8a365c1b2bd9ac9faa
    Signed-off-by: Shobhi Jain <shobhi.jain@intel.com>
    (cherry picked from commit c31edc5ab9013d93ffd32ed72adb14740e43b24a)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 3de47d0..88b23a6 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 3de47d08fc211cc2afdcf7a0411e84fc9ae3f948
+Subproject commit 88b23a66e761d7a6f14d3bdafe72ef0cdb668a42