Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - 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>
    (cherry picked from commit 60b2c02f3968d84df339b491d659b6549bfc3771)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 410fdb1..bd5e747 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 410fdb1fdbe2f51ff3939eccfd068920f597fe4e
+Subproject commit bd5e7473199c3ff00ce212a635453cc938387a92