Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - test_env_action: speedup unittest, don't sleep

    Change-Id: Ib662032e5133b8fead1c6858905bd13ca40f4dd6
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 90e5786..dde516e 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 90e5786f6e5bd3235e3d1c307782b8cae9d7b958
+Subproject commit dde516ea4da0d754a12c8435a91589820f48d141