Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - Merge "tc_heat_rfc2544_ipv4_1rule_1flow_64B_trex.yaml updated" into stable/euphrates
  - tc_heat_rfc2544_ipv4_1rule_1flow_64B_trex.yaml updated

    Change-Id: Ie9cee3e0567e771cbf11a9802bd33a420cc1ee7a
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit 041aeb7d3505e98af5b167a5ee05bb72c3c87a26)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index b5d1171..9cf89a0 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit b5d117109e9d3918376f5bd307e7eff69ff33d2d
+Subproject commit 9cf89a084b3f5840f6085aedc76ed93be8b5aec6