Update git submodules

* Update docs/submodules/yardstick from branch 'stable/danube'
  - attacker_general: fix logging to use %s

    Change-Id: Ib451d7883eb5df13cfe95477cea43c076ac0452a
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit 45f46d5220cbfa89224d55caf94a079fccd2679f)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 77d3868..d3ed2bf 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 77d38685b12e968147432649d0546eeb97319e39
+Subproject commit d3ed2bf1e8c477e013b548e7df9eada07512bf85