Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - Merge "NSB: update vfw tc_heat_external tests" into stable/euphrates
  - NSB: update vfw tc_heat_external tests

    rename xe0, xe1 to uplink_0, downlink_0
    enumerate tgs/vnfs starting from 0.
    add disable_dhcp

    Change-Id: Ia4f08b3ad5ab298192c249d04b10a6efbe4f210e
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit b3a48eddc398c23523e379e6838160d456cf4368)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index f21e473..0de44ee 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit f21e47326025eb8e9d45170a93d7ec43128c1f77
+Subproject commit 0de44ee068f246af766b7399574d1abfe95e1fd3