Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Allow to see steady state status in the yardstick logs"
  - Allow to see steady state status in the yardstick logs

    Change-Id: Ic2281b300ed1de6ecd3daf14b5273db22688de8d
    JIRA: YARDSTICK-1454
    Signed-off-by: Ameed Ashour <Ameed.Ashour.Ext@nokia.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 820b817..fdd8206 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 820b81753dc50ccd8762806f2d5c8398c319c4a0
+Subproject commit fdd8206d8f3d456fa3e3b56630e7449d55a71258