Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - Bugfix: Add opnfv_os-nosdn-ovs_dpdk testsuite for Compass4nfv

    Change-Id: I35e6471bb561eb773bd188b36b912969188955d2
    Signed-off-by: JingLu5 <lvjing5@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 85c119b..204bed2 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 85c119beb49b545bcfa6bfbf1d25faff5648fa8c
+Subproject commit 204bed26efa57ca0de15534d9268bb4d61f7e0fa