Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Cleanup Plugin unit tests"
  - Cleanup Plugin unit tests

    Removed unneeded output (LOG.info and print functions).

    JIRA: YARDSTICK-1274

    Change-Id: Ida3b62ce28e27058a8b4a3a9e6fa16f041a1f99c
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 1f1aed7..6f1dede 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 1f1aed7a38925abff83d655209a9b926b2244ea7
+Subproject commit 6f1dedee119f15bdbff5dc2832522b1a67147065