Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Create test suite for Euphrates release

    JIRA: YARDSTICK-814

    Test suite:
    "opnfv_os-odl-fdio-ha_daily.yaml",
    "opnfv_os-odl-dvr-noha_daily.yaml",
    "opnfv_os-odl-sfc-noha_daily.yaml"
    are missing in yardstick-apex-baremetal-daily-euphrates job.
    We need to create them.

    Change-Id: I6d8bbeb17cd887776f1f3b401ec80523ea90d3c1
    Signed-off-by: chenjiankun <chenjiankun1@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 1bd39dc..6ecb9a6 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 1bd39dc28a422c98d95451d9893c51bf3867806c
+Subproject commit 6ecb9a6d50345277645633b1bed4d255dc434222