Update git submodules

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

    Remove redundant functions:
    *get_instances
    *get_instance_status
    *get_instance_by_name

    Function create_instance_and_wait_for_active now uses shade client.

    JIRA: YARDSTICK-1088

    Change-Id: I766da333dabbb1b83a7b4ede4bf73567ec70eb8c
    Signed-off-by: Shobhi Jain <shobhi.jain@intel.com>
    (cherry picked from commit 069d7a13d1f8b6b465ae164e2a440c25270f7e8e)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 135f472..8c76399 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 135f47250e9253d5065fa4c51550d131739412ec
+Subproject commit 8c76399ed61bb1256dddab909a23838cb6fa498e