Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - BugFix: Negative dropped packets in Prox tests

    Removed the abs function which can potentially mask
    negative dropped packets.

    Dropped packets in Prox workload VNF = max((tx_packets - rx_packets), 0)

    Change-Id: I510a351e899cdf9a1f366d632b9f0528b1d9dcce
    Signed-off-by: Abhijit Sinha <abhijit.sinha@intel.com>
    (cherry picked from commit a27278dacaa54ae60cd3bdfa6e6145643f76fa02)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index b3ebb05..c0b3d5a 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit b3ebb0526501cba14055e00ee16606f85f6212eb
+Subproject commit c0b3d5a7abc6acd0282c063844471ed6aa02d36b