Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Add ODL noHA testcase"
  - Add ODL noHA testcase

    This testcase confirms the resiliency of Opendaylight
    in a noHA deployment

    SPEC: https://gerrit.opnfv.org/gerrit/#/c/49245/

    Change-Id: I810011c35c7bb6377f9295330cf7122d10cf74c3
    Signed-off-by: Dimitrios Markou <mardim@intracom-telecom.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 57006b4..e4c7ab6 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 57006b47150d2999a28e4af9a956e4b30f099e87
+Subproject commit e4c7ab64f6886b74e3725967d048801e879b3ec4