Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - NSB: update vfw scale-out testcases

    Change-Id: I6bd8a87f70954f288975e3e73e3cfbd36ae561dc
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit 39ead7aee3610dddbdeae33a5776ae5b98dfabea)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 0389453..b529585 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 0389453486af8b58f77a65a6455068fe95346e47
+Subproject commit b529585719b1ce0494090ec5dbb52a2be0668bb5