Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "add support of dpdk for bottlenecks_ping"
  - add support of dpdk for bottlenecks_ping

    This patch is supposed to be coordinated with
    https://gerrit.opnfv.org/gerrit/59901
    to support dpdk scenario for Bottlenecks

    JIRA: YARDSTICK-1332

    Change-Id: I4ae3d05523d0624d689702cb8eb23be364830de1
    Signed-off-by: Yang (Gabriel) Yu <Gabriel.yuyang@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a3d1c85..3eb7c80 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a3d1c85482159201492284d1c893cebda91003b3
+Subproject commit 3eb7c80aa614456b05e08651a55f7450e6864c79