Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - Merge "add VNF scale-up template" into stable/euphrates
  - add VNF scale-up template

    adjust worker_threads based on number of vcpus

    Change-Id: Ie5444a64c15711a0e813905c69581f189432fe0b
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit bc6c77102684f69bccdce8509723e00ef38c69cf)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index bf8aabd..63679e6 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit bf8aabd918a6639bce5382ac6f905cbcb79d8815
+Subproject commit 63679e6c68f6d3d881e222351785660dcac93f73